Title says it all.
I’m thinking of buying a bigger Lego set for my two children ( boy 9.5 and girl 7.5) and didn’t realize all the bajillion options.
A little guidance is appreciated.
Its great, isn’t it? 
So far my little one is only spread Duplo about the floor, hopefully she’ll get to appreciate the sets more in the coming months, especially since they sell “Thomas the Tank Engine” sets.
When we were younger Dad used to get one or two of the specialised sets and bulked it out with one of the big buckets of blocks. Not for the economy, but to try our imaginations.
Speaking from my own childhood here: Get a Star Wars set for each of them. They never had them when I was a kid.
I would go with Pushkin’s dad; get a set design one and a box of many blocks. Half the fun of those design ones are “improving” on them.
Oh, man.
I see that Lego still sells big tubs of just bricks–which I really don’t see too often in stores; everything is a ‘set.’ So I highly recommend those.
However, if not those, then my recommendations would be based on how your kids play with legos. Do they like to play with what they build, or do they like the building? Because some sets, like the Viking sets or City sets or AquaRaider sets, result in a really great, fun-to-play-with thing. But if they are less likely to play with what gets made, then I recommend the sets that allow you to use the same bricks to build 3 different cool things. I think they’re called “constructor” or something. Like one lets you build a great T-rex, but use the same bricks to make an awesome bat and then something else. Or make three different kinds of trucks.
My son plays a little with what he builds (depends on what it is) but he’s just as likely to either put the completed piece on a shelf (so it stays intact) or break it up and make something else with it, either from LEGO instructions or his own imagination.
When I think of Legos, I think of stepping on them in the dead of night. I honestly believe my children leave them as a minefield.
A few Lego products went over pretty well at my house.
Lego table. This was a short table with storage for the sharp little pieces and a large “base”, so construction has a stable platform. My son was a bit younger when he used this item (maybe 6-8) but he lived at that table.
Theme sets: Ya gatta have one or two of these - Pirates or Knights or Ghosts or SciFi. These have the special pieces that go beyond simple rectanges. Plus, if they have a lot of theme sets, kids can create fun situations like pirates with damsal hats fighting knights in dresses.
More, more, more: Yeah, like Cranky said. The tubs are nice (til you have to clean them up).
Would you consider branching out ot the Lego Mindstorm sets?
(Yes I’m an adult, and I think they’re WAY COOL!!!)
I find many of the modern Lego sets to be really inflexible to the extent that they’re almost a single-purpose assembly toy, which I feel to be a disappointing departure from the traditional ethic of Lego where they supply the parts and the child’s imagination assembles the toy.
So I would suggest picking up a collection of assorted Lego pieces on eBay, pick through them by hand (there are always a few chewed and broken pieces, plus an assortment of interesting non-Lego toy parts, and a few bits of weird stuff like raisins or bits of hairy Blu-tack).
After sorting by hand, most of the pieces can be sewn into an old pillowcase and washed in an automatic washing machine on a cool cycle, or an overnight soak in a bucket with some dishwashing liquid follwed by a few rinses is just as good. (Parts you probably shouldn’t wash include those with paper labels, and complex things such as the compass, magnets, electric light bricks etc).
I’ve got (well, my kids have got it) a big, big box of wildly assorted Lego that came mostly from eBay, and it’s far more playable than any of the big pirate or space sets.
My favorite set is the Lego Life-Size Eiffel Tower — though at $85 million retail, it’s not for the thrifty. You’ll probably need a big back yard too, and lots of tarpaulin for when it rains. I only built mine once.
Lego Nineteen Eighty-Four is a good choice for older children who can handle the difficult subject matter, or just those whose collection is low on gray bricks. This set includes the very rare head-cage-full-of-rats piece in it, which is hard to acquire otherwise. I think Lego Dentist’s Office is the only other set that has it.
I can’t recommend Lego Waiting for Godot. It’s a skimpy set, and quite the rip-off for $40. In fact, I’m not fond of any of their Samuel Beckett series. Try Lego Twelve Angry Men if you’re going to take that route.
Whatever you do, don’t get any of the Lego Anti-matter series. Although they’re intended to be educational sets — particularly for teaching the laws of subatomic particles and the physical equivalence of matter and energy — the lessons learned tend to be very short-lived.
I’m still in the duplo stage. However I go with the approached espoused by Pushkin’s father. Get some specialized sets for the fancy pieces and then get the tub of bricks for creativity. What we are planning on doing is keep the instructions for the fancy sets, and then sorting the legos by type of brick and throwing them all together. Then you can build any of the fancy sets you want and still use the special pieces for creativity when they’re not in the fancy set.
One thing - don’t forget to get some Lego people. The kids love having the people to play with. My son has his duplo skeleton (from a pirate set) doing everything - driving Thomas the tank engine, flying the plane, driving the airport luggage car, etc.
Or four small yards, strategically placed.
I used to think that, but then I discovered the Lego fan sites. There are people out there using weird parts to create all kinds of crazy stuff. Examples:
“Sweetpea” spaceship
some minirobots
“Calamari” space fighter
“Quetzalcoatl” mecha
another spaceship
Granted, one of these custom models may have parts from 20 different official sets. But you can build things that are just not possible with the basic 2x4 bricks.
Thirding this. My sister and I were both Lego fanatics. I was never much into the actual sets, but if nothing else they give you some neat-shaped blocks you wouldn’t get otherwise. Beyond that, it’s all about the big tubs and imagination.
-NinjaChick, who at the age of 21 is not ashamed to admit she still plays with Legos.
When Bonzo was Lego age, he was a Lego fanatic, and he too found that the specialized sets were kinda boring, because once you assembled your Bionicle, then you were done, and there wasn’t anything left to do. And the Bionicle could only ever be…a Bionicle, unless you dismantled it and turned it into something else, but then it wasn’t…a Bionicle. Which seemed to defeat the purpose of the toy.
He had a lot more fun with the Big Tub O’ Blocks (we actually had two tubs’ worth, which meant he could create really humongous things like a T Rex) and the specialized sets came in handy for odd little bits ‘n’ pieces that you could use to embellish your basic creation.
When you’re looking at the specialized sets, look for components that are generic in shape, i.e. that can have more universal applications, rather than specific components that can ONLY ever be, say, a Bionicle blaster. Look for components that can be windshields, wheels, wings, shrubbery, etc., rather than lots of specialized accessories like guns, swords, and helmets. In his day he had the Robin Hood set, and he never used the teeny bows and arrows or the falcon that rested on somebody’s fist, but he used the tree and fortress components all the time.
There are some Creator sets that fall halfway between the buckets and the specialized sets, like set 6164, the Rescue Building Set. From the Lego catalog:
The Creator line also has things like 4894 - Mythical Creatures, with cool themed pieces. I haven’t seen these Creator sets “in action” (we’re still shopping the Duplo section), but I like the way they look on the toy store shelves!
By the way, if you’re short a particular type of block to finish your masterpiece, all of the Lego brand stores have bins you can by from in bulk.
Dad would be pleased to hear his vindication 
The big buckets might have looked frustrating to me as a small kid, drooling over such nice things as the Blacktron moon base (which my grandfather bought for me just as I was supposed to be studying for a big exam at age 11) in glossy catalogues, but the big bucket of bits made sense in the end. Just try not to end up with too many bits that are of the same colour if you can.
I found the best to be a few buckets with every type of block place some flat pieces .ect
And the green square floor pieces so you can build stuff up form the ground.
I got some small lego car sets from a Doper in a Secret Santa exchange. That was fun to play with in my cube.
I’m starting to think I should get a buig bucket for myself again.
For older kids the Porn Lego kits are popular:
http://drew.corrupt.net/bp/series1.html
http://drew.corrupt.net/bp/series2.html
up to series6.html