We stayed in two resorts last fall. Because of how much DVC points run on the weekend vs. weekdays, we spent Saturday night at ASMu, then moved to BCV on Sunday morning for the rest of the week.
First, I will have to admit, in theory it sounds like a great idea (splitting resort, that is). But take the time to organize for each resort stay. We actually didn't arrive to AS until 1am Sunday morning. I wasn't as prepared as I should have been and we unloaded more than necessary. Therefore, we had more organizing to do the next morning and more loading up the van than I would have liked to. So follow the wise advice of packing separate bags for each resort. (If you're flying in and not renting a car, then you'll have to take it all with you, though.)
Second, you may ask for someone to pick up your bags and transfer them to the next resort. This service is available at no charge. You should arrange this the day prior to checking out. We requested someone to pick up and when they weren't there when we were ready to leave, they said that it would be fine to just leave the bags in the room. I (being a little distrustful) reluctantly did so and everything arrived at the next resort just fine. We left a $20 tip on top of our luggage for our 10 bags and I think that helps (wink, wink) to ensure your luggage is taken care of.
When we left ASMu for BCV I kney there was a good chance we wouldn't be allowed to get in our room until late afternoon, so we kept out our swim wear, a change of clothes, hairbrush, makeup, etc. We also kept a few snacks with us. (This is the part about organizing. I should have packed a separate bag for all this long before we set out on our trip.) As I guessed, we weren't able to get into our room until about 3:30 and we had HDDR ressies for 5pm, so we were cutting it very close. There are bathrooms by SAB and we could have changed there, but we were really wanting a bath after swimming in the sand-bottom pool. So my advice here is plan little to nothing in way of ressies on your "moving" day if at all possible, or head out to the parks for the whole day. The stress of not knowing we would get into our room before dinner was a little unnerving for our family of 6. Our good fortune was they my brother and his family had checked in to BC the day before and would have let us shower and change there if necessary, but I couldn't see that happening with one bathroom and 6 people.
So, I guess what I'm saying is BE ORGANIZED. Changing resorts midway (especially if you have small children) can be stressful if not planned out. Always save the most desirable or more deluxe resort for last so your last impression of your vacation is more memorable (hopefully). And be flexible on moving day in case you're not "settled in" until late in the day.
Good luck.
PS. Would we do it again?? Not if I can help it. I would select the most desired resort for our family and stay put. But in the case of our last stay, I was not about to pay out the nose for our first night when I knew we wouldn't arrive until very late Sat. night.