Wheels, sloping bricks and clear blocks were the currency of my childhood. Inverted slopes could have just as easily be made of platinum for all we wanted them.
I think it would be great if they made duplo-lego interface blocks that allowed you to build gigantic things with duplo and then add detail with lego. (are you hearing, lego designers?).
There’s no ‘S’ in ‘Lego’.
Well, that’s the whole point of Lego, you don’t need to have an S, you can build one yourself.
I always thought they did. I have none to hand and the Duplo back at my parents I was going to pull out for my daughter has gone missing, but I thought the big hole under the Lego block fitted into the big hole on top of the Duplo base.
FTR, I’ve already seen a couple of post-thanksgiving sales (K-Mart and I forget who else) for next Friday and Saturday that have discounted lego sets. This week might be a good time to pick some up 
Any block that’s a multiple of the basic 2x2 block (e.g., 4x2, 10x2, 6x4) will interface with Duplo, so it’s easy to build things combining both.
So much for my path to fame and fortune. (and sucky that there are very few Duplo bricks at home, it is mostly Mega Block)
Piling on. Basic Bucket O Lego supplemented with the occasional kit or two was the menu of entertainment when I and my siblings were kids. We built the heck out of the basic bricks even if the Special Sets were an Occasion.
I still remember trying to do a bit of stop motion animation with my dad’s video camera and a small Lego background. 
Unfortunately the double-clicking required for the framing was a bit of a pain so that didn’t get too far off the ground, but it was cool.
Whenever my brothers got another Lego box, the procedure was:
That definitely didn’t make “fancy” pieces like wheels necessary at all
You should pick one set at random and see which pieces your kid gravitates towards. Then buy more of those.
