I'm here!
Phoebe, that sounds like a fun trip you have planned!
Shopping in Orlando offers plenty options. There are about 2-3 outdoor outlet malls covering every possible retail store in the US, well almost all of them anyways. A little note of warning though - these outlet malls are always packed and busy and personally, I find even half a day at one mall a little exhausting, especially given the heat. The Mall at Millenia is also an outdoor mall but non-outlet and offers a better shopping experience, with more of an upscale feel.
I love shopping in Miami! Especially because I have access to stores that we don't have here in Tampa. Especially the area on one end of Collins Avenue. You have stores like Club Monaco, Mango, Guess, Armani Exchange, Versace, Bennetton, etc. There are a few malls outside of the Downtown Miami/South Beach area and I've only been to Aventura Mall which is also quite nice.
Where on the west coast will you be spending time?
As to what to wear- what Angie said - we're seeing 95 deg highs these days Oh, also some rain gear - you can definitely predict some unpredictable spots of rain