Family of 4 here. Here's what we do:
check: 1 large suitcase at least 2 "carry on" suitcases - usually expanded - at least on the way home

carry-on: one case and one personal item for each person (the "cases" are usually our camera bags, back packs with activities, dh's computer)
Each person packs about 6-7 outfits (we stay longer, but do laundry at our villa). I also will pack jackets and all of the regular WDW gear (ponchos, our very useful chamois packs, fanny packs or day packs for the parks, water bottle insulated bags, water shoes for the water parks, etc.)
The kids arrange their outfits with socks and underwear and we put each outfit in a zip lock gallon bag. I even number the bags and then there's no fussing early in the morning over what to wear. I just toss the bag to them when they wake up.
Dh and I don't use bags!

We just fold and stack our clothes by outfit (ok - I put the socks and underwear inside and fold the shorts over to make little "packs"). That way, dh and I can get ready without fussing also! That also helps me to know what day I need to do laundry. I stuff or roll the small stuff in the open spaces (pj's etc.).
I've taken bug spray but I'm not sure I've ever used it. I think the only time I did (or needed it) was at the FW campfire.
If we're staying one night in a different location before our main stay (as we are next week), I pack an over-night case (or 2) so we don't have to get into the big one.
I also like to pack a few bags within the suitcases. Our swim stuff is usually together in a beach bag. I usually put a collapsible net laundry bag in as well.