Most of the pp's have given you the reasons. I will rate the reasons why we love splits
1. The amenities- We SS in order to do the stuff at each hotel. For example, SS between POFQ and WL. We stay three nights at POFQ- the boys get to swim at both the POFQ and the riverside pool. We spend one night taking the boat to downtown and eating, shopping there. I get to know the friendly bartenders at Mardy Grogs, River Roost, muddy Rivers and Scat Cats. Then we head to WL for 3 nights- Boys get the pool, the bike path, the water sprites and I get to meet new bartenders at Territory Lounge and Trout Pass. We get to eat at Whispering Canyons. We enjoy the boat to MK and also the one to CR and the monorail. And, we get to watch the water parade from the balcony over the lobby with the music piped in

.
2. Convenience- Yes, it is convenient because we arrange our park days to follow our SS. Water parks, Studios, downtown and AK while we stay at POFQ. MK and Epcot via the boat to CR and the monorail while we stay at WL.
3. New Rooms- Something about just moving to a new room, a new view, a new maid, a new experience.
4. Savings- Yes, splitting does save because I can convince all that we stay in a mod for the first 3 nights, then splurge on a deluxe the last three.
5. Satisfy everyone in the family- This hits us as each person likes different things. My daughter loves WL while my boys really like POFQ. SS's make both happy.
But the most important thing that allows us to do this is-
Disney makes it so easy!

Really, they make it seamless if you know what you are doing. As we drive down, I just have the wife and kids head to the park on the bus. I take our luggage or have bell sevices transfer it, whichever I feel like at the time (usually depends on our room location at first resort). I drive the van to new hotel and head to the park to meet up. They get a few moments away from dad and I get a leisurely trek (did I mention I quickly run to meet new bartender

) to the park that morning.
Oh, and as for packing- We always pack light. 3 or 4 outfits each and most are shorts and t shirts or the like. I prefer to do one afternoon laundry day than pack for the full 8 days. Helps with travel. Lundry day is last day @ POFQ and I wash/mardygrogs/rinse/mardygrogs/dry/mardygrogs. Flies by.