Last year on the Panama Canal cruise that is exactly what I did - layed out all my outfits and then only packed the ones that would match the 1 pair of dress shoes, 1 pair of dressy sandals, 1 pair of sneakers and 1 pair of Tevas I took. Everything else went back in the closet. Ironically after packing everything I realized after rejoycing of getting everything into 1 suitcase that I did not put the shoes in.
I personally love red-eyes. That is my 1st choice flying from CA to PA. Granted I can sleep anywhere and I always try to get a window so I can lean. I heard if you want to change Disney Air there is a non-refundable $75 deviation fee that they will charge (not sure but guessing it is per person).
As for the hotels in Barcelona. Personally I think the rates that Disney is quoting are ridiculous. I was on the Med Cruise in 2007 and booked my own hotel (but at one of Disney's) for much cheaper. I was able to use the cruise line desk they had set up there and even add on the transfers to the port (for a fee, but they took our luggage and everything). In 2007 I stayed at the Hesperia Presidente (which is not one of the hotels this time).
I have started to make a spreadsheet of the hotels in the area (I am a little over 60 at this time). I am noting what prices are right now for the same days in 2009 (both from their websites and hotels.com) Most hotels should start to open up reservations about 1 year out. Personally for me I am looking for hotels within a few miles of Plaza de Catalunya. This at the top of the La Ramblas - very centrally located to the things I am looking to do. If anyone is interested I would be more than willing to post the spreadsheet to Google Docs.
Here are 2 links about the different neighborhoods.
From Trip Advisor
From Barcelona Man