The Riverside Marriot is fantastic! I stayed there 2 years ago at the start of my trip, and cancelled the hotel I was going to stay at, at the ens of my trip just to stay there again.
The grounds are beautiful, the pool is wonderful, there is an evening music/dance performance that I went to twice, breakfast buffet is incredible and if you get a room with water view, you can observe daily life on the water. (The spa is too expensive - get your massages on other parts of your trip)
It is not as central as a town hotel, but water taxi's are easy, and I wouldn't trade the ambiance for anything! Book it!