Hey there!
As far as clothing goes, this is kind of a broad question. I've been down in both summer and fall. I'll also make the assumption that you're staying at the parks for the whole day without time to go back, as I've found this to be the majority of cases. In Florida, the weather is the biggest deciding factor. In the summer, the baking heat calls for something light and airy. Try a larger t-shirt that's made of cotton or microfiber, as those are breathable fabrics. Shorts are also a great call, but avoid jean fabric because it will stick, chafe and rub. The dye can even come off on you from sweat if they're cheaply made. Grab some good sunglasses and leave your jacket behind. I've found that dresses or skirts can personally get a little hard to manage in the seconds you have to get on a ride...especially if it's a coaster where you also manage bags and a restraint. In the winter or fall, it can sometimes get down to a chilly 50 degrees. I wear a t-shirt and a light jacket and capris or jeans. Keep in mind too that some restaurants have dress codes that you may need to pack something nicer for. Refer to Disney's site for instructions on that, but I've worn a dress and sandals for one and been fine. As far as shoes I usually pack some higher-end ones and buy a pair a few months beforehand to break them in. Brands like New Balance, Hoka, Brooks, Nike, Under Armor, etc, etc, are great to wear in parks and are generally made well for use afterward. If you have accessories like glasses or Mickey ears, consider either not taking them (contacts are your friend!!) or picking up a glasses holder (an adjustable band for the back of your head to hold them) as they work to keep both ears and glasses on.
Okay, now there's the question of where to look. For bottoms, you can look at department stores like H&M or Aeropostale or even Kohl's.
Walmart is also a good spot if you're willing to dig because they're cheaper. For shirts, you can order iron-ons or
shopDisney ones, but I've found pop culture merch sites like Hot Topic, Box Lunch, and even
Amazon are more reliable and cheaper. HT and BL also sell harder to find merch for things like Kingdom Hearts, mini backpacks at half the price of Disney's, and other things you won't find on Disney's sites or properties. I shop there before anywhere else.
Whew! I think that's it! I hope this helps!
