Op - I love split stays, my son (adult) puts up with them but isn't a fan. I think there are a mix of loves and hates and it might depend on your group make up and if you have a car or not.
We didn't start doing them until my son was an adult and we drive down so have a car. I did my first one when I was renting points at OKW and couldn't get a room for my entire stay so I did a few days at OKW and moved to BW. I fell in love with split stays then. Now, I tend to do them with the first night or two at a value or moderate resort then move to an Epcot resort. My thoughts are that we arrive between 1 and 3 then always head to a park so it's not worth paying deluxe for that night. Then, I know you have to take a bus to AK so that is usually our second day. We don't split with MK/Epcot simply because MK is a half day park for us. We will hop over there maybe for a hour or two during the week but we never spend all day there.
I unpack, my son does not. Usually I do a small bag for the first stay and put my laptop and my hanging toiletry bag in a tote bag. For the second stay, which is usually longer I pack a little bigger bag. I stick my dirty clothes back in bag #1 and my pjs in my tote bag. If I think I will use a swim suit at stay #1, I put that and a cover up and my pool flip flops in a packing cube. Easy enough to pack those back into the cube if they are wet on move day. If they aren't wet, I just transfer that cube to my other suitcase. We go to resort #2 in the morning and drop our bags off at Bell Services then head to a park. Bag from resort #1 stays in the car. Move day takes zero time away from our park. My son just uses the same suitcase for both stays and if he has a wet bathing suit, just puts it in the laundry bag that's usually in the room or a trash bag and sticks it back on the top of the suitcase. Takes it out when we get the room in Resort #1 so I can wash it out and hang it up.