I’ll share a few more thoughts about screen houses and canopies, though I think other perspectives, such as Harmonious Discord’s, would be helpful.
I was thinking of the old-fashioned kind, which I find a pain to put up whether the frame is internal or external. They never seem to spread out evenly, and I usually find the doors to be troublesome. However, there are newer designs like this and this that look to be much easier to deal with both in set-up and in use.
If there are a lot of bugs around, a screen house can offer respite. I still think it’s wise to use insect repellent on one’s body (you can’t stay in the screen house all the time), but even with that having a bunch of flies buzzing your dinner is unpleasant.
If there’s a stiff breeze but a desire to read or play board games, the screen walls make it possible to do those things while still being outdoors. Likewise, with a driving rain the water will be slowed down to where one could sit inside and not get sprayed, though it will come through the walls to some degree.
Kids may like a screen house as sort of a playhouse (though that may be a problem if, for example, the dinner table and chairs are set up there).
A canopy has an advantage in versatility due to its lack of walls, particularly in where it’s placed. It can be right outside the tent as a sort of large foyer, it can be positioned over a picnic table, it can even be put over the fire if it has a peak vent to dissipate smoke. Because it can be walked through, it’s less of an obstacle in camp and more conducive to interaction between those under it and those outside it. It’s also easier to move should that be desired.
Of course some of the pro/con between the two is dependent on the particular weather, which is tough to predict over a ten-day period. Either one will be of use; which is better for you is hard for me to say.
After preview: the purpose of a groundcloth is to protect the tent floor from abrasion. If it’s a nylon floor, I’d sure want it under there. If it’s a poly floor (like a reinforced plastic tarp), it’s probably not necessary. IT SHOULD NOT PROTRUDE BEYOND THE TENT, in fact should be recessed a few inches from the perimeter (won’t collect rainwater that way). Having a liner inside is not a bad idea (may or may not be worth the trouble), but I would not forgo the protection of a groundcloth for a nylon tent.