I can only advise about vessels I have been on recently.. Please refer to my posting about disabled cruising, my posting August 26 and duplication August 28. The ship was not the Sun Princess but the Sea Princess. While the "wheel chair accesible"staterooms may be adequate, the ship in my opinion is not wheel chair friendly, that is easy to get around. The Sun Princess is an identical twin of the Sea Princess. I have had no need to have a special stateroom. I have found on the newer Holland American ships and even the Carnival Elation it was easy to get around and use of elevators.
Terry, I can recommend Celebrity, esp. the Zenith which we enjoyed a lot going through the Panama Canal. Most of the newer Princess ships are good, including the Grand Princess, although the showroom leaves much to be desired for wheelchair users. I have not been on the newer Royal Caribbean ships but have heard very good stories about their access...even lifts in the pool. Currently I am withholding any recommendation for Holland American until we return from our next trip, which is with HAL in South American in November. Carnival is more crowded with smaller cabins and I would not recommend this line for disabled cruisers.
I was just on a cruise in september to the western caribbean on the Grand Princess and would do it again in a minute. The ship was completely wheelchair accessible including an outside stateroom with a balcony.