Another BBW here.
When we did WDW in September of 2007, I found that the name of the game was comfort. Several thing I brought with me never got worn, cause they were really cute, but just not as comfortable! When it was hot, I didn't want anything to be tight or restrictive.
One of my favorite things to wear was my divided skirt. It was just below knee-length, loose and kind of flow-y, and made of a slightly thicker T-shirt material. It was navy blue and matched a lot of my shirts. I think it originally may have came from Roaman's, but I found it on eBay. I also loved my yoga-shorts. I found them at
WalMart, they are styled like yoga pants (knit, slightly drop-waisted) but end just above the knee. I got a couple in different colors, and they were very comfy. I also had a couple of pairs of knit shorts - NOT tight, and longish - kind of bermuda length. I do NOT do short-shorts. I had T-shirts and tank tops (tunic length) that matched all of the different colors, and that's what I wore the whole time I was there. Yes, my upper arms were not the most attractive in tank tops, but dang it, it was HOT.
I also packed a couple of dress-ey outfits. We had some nice dinner reservations, and it was good to get out of the casual park clothes. I took a couple of broomstick style skirts, and one long, A-line style knit dress with palm trees embroidered on it.
As for shoes, I wore nothing but my
crocs. I am a croc addict, and I swear by them. My feet were usually comfy - I don't think ANY shoes can stop your feet from hurting after 10 hours trekking through the parks - and I never once had blisters. Just don't take
new shoes, make sure your feet are well accustomed to whatever you take.
Finally, plan well with personal supplies like deodorant, moleskin, body glide, advil, etc. Although you can buy most things at WDW, it is horribly much more spendy. Be sure you pack enough.
Ok, one more thing. And this may be TMI. So consider yourself forewarned, gentle readers.
You know how sometimes we BBW ladies end up with a nasty little fungal infection in our creases when it is hot and damp? Red, weepy, and ouchie? My Dr told me that it is basically the same infection as athlete's foot and jock itch. You can buy the same cream that ladies buy for a yeast infection, or - much cheaper - you can go to the foot care aisle in WalMart and buy a tube of generic athlete's foot cream. Much cheaper.

I never travel without it anymore, cause it doesn't happen very often, but BOY when it does you want relief and you want it NOW.
have fun on your trip!