We've stayed at all 3, CR, swan and dolphin. We didn't think the money for the CR was worth it. Its considerable cheaper at the swan and dolphin.
It may have just been a monorail ride over to epcot, but one long ride. Since MK resort area is so far north, you are just so far from all the other parks, so it takes forever to get there.
It does depend on where you want to spend most of your time. With a little one, you may spend all of your time at the MK. We just liked being close to the hollywood studios and epcot. There are lots of places to eat at the boardwalk area, and your close to the y&b club too, as possible dinner locations.
If your mom has mobility issues, you can rent a
scooter offsite, and drive easily on the boats and Swan and dolphin, and onto the busses too. THe disAbility board, sticky has the rental info for some offsite locations.
We likes staying at the dolphin vs swan because its closer to the 24 hour food place it was tubbies, I think its called picabu now. If you head over to the Theme Parks Attractions and Strategies board there is a sticky thread with the discounts and availability of the discounts for swan and dolphin.
Someone also mentioned you cannot get the dining plan or magical express from the airport to the hotel with swan and dolphin. So, if you really want that then its CR.
Connie