We just returned from Explorer of the Seas with the Eastern Caribbean. Basically, the lady who helped us set up our excursions was way off base. We started to do the Rain Forest Tour which she said would be accessible if we could transfer to the vans. The tour guide met us first and said it was NOT accessible in any way. He said the trail they would be on would not be wide enough for a wheelchair. The explorations manager gave us a refund and we took a taxi on an island tour. It couldnt have been better. We had a great taxi driver. There was one excursion through Royal Caribbean which had a wheelchair accessible van. The night before we arrived, we were called to let us know the van was broken down. Once again we just got a refund and went out on our own. We did that at every port and it worked out great. It was usually just our family and a few times we met up with some people and they rode along with us. Those are much more low key and you can have more options of where and when you stop for pictures, etc.
If you have any more questions, feel free to email me and just put cruise on subject. I will be glad to help you in any way I can.