My inlaws have the Buick Enclave and love it except for the seat comfort. He's slight and finds the lack of lower back support to be painful. Everybody is shaped differently, so be sure to give the seat a good test. Its possible that a higher trim level came with better seats.
You'll have more storage space for the wheelchair in a SUV with only 2 rows of seats - a 5 passenger SUV, rather than a 7 or 8 passenger model.
I personally find those big Tahoe, Yukon, Silverado, Sierra bucket seats to be very comfy. Something like a Honda Element might be easier to get into for its height and easier to park in the city but I'm not sure about grab handles on it.