Meh, I wear whatever to amusement/theme parks.
This is actually my first WDW trip (leaving Wednesday morning!!) aaaaand I have 4 tank tops, a pair of capris, a pair of pants (sleeping/lounging, comfy!) two pairs of shoes/flipflops packed in my bag. I'm chunky, I have chunky arms. I don't really give a crap. I'll brush my hair, my teeth, put on some makeup (not alot!) and luckily for the rest of yall, deodorant before I leave the hotel room.
I just need to look "good enough" for photos. Really, anything above that is a plus.
edit to add: I bought three new tank tops for this trip, specifically. LOL Does that count for anything?