OK, Since you are going to be at BWV and need a room for 5, I would suggest seeing if you can get one of the really great rates that Swan & Dolphin has occassionally. I think you would really enjoy the close promiximity and having 2 heavenly beds. Of course, a good rate for S&D is about $149/nt. but you would only need 1 room.
If you want to go really cheap, you may want to try the Comfort Inn Lake Buena Vista on Palm Parkway. They sometimes have rates for as low as $49.00 However, with the CI, you get what you pay for.
As for staying at a value for luggage delivery...I think I would pack an overnight bag and leave the rest of your stuff in the trunk until you got BWV.
BTW, I think the luggage services at BWV is the most impressive service I have ever seen in a hotel.

There is nothing like parking your car, handing someone your keys, and walking into the hotel for check-in. We are DVC so we get free valet service. Wonderful.
((I started to say that there is nothing like parking your car and never seeing it or your stuff again...but...errr...umm...well, that has a totally different meaning, doesn't it.))