Any of the Voyager class ships.
See my article at
It has been reprinted a numner of times, but it's fairly indicitive of what you will find on any RCI Voyager class ship.
The Monarch is really old and retrofitted -- I would not actually recommend it. You need to look for newer ships -- constructed since 2000 for the *best* access.
Editor, Emerging Horizons
***edited to remove commercial link*** -- the only magazine about accessible travel