TThe Divi Flamingo on Bonaire would've been my choice also - they mention their HSA involvement on their website. Another that recently hosted a group is Cap't Don's Habitat. One thing I'd look at also is the boat info on their websites - many have wide swim steps right on/above the water with good ladders. Others like Bonaire Dive/Adventure - while a good outfit, have smaller panga style boats that make it almost impossible for you to do anything but a
backroll off the side. They will take your gear because they have side board ladders. On Bonaire, I found the boats at Toucan Divers to be easy access, they're lower, smaller and had good ladders/swim steps.
What was posted about your upcoming Catalina dive should be emphasized. Do not go there expecting assistance without prior arrangements. In many cases the captain drives the boat and the DM counts heads on/off - most of the time they don't get in the water. SoCal divers frequently bring their own gear - including tanks - and are very self-sufficient. So you'd want to make arrangements in advance - maybe even hire a private DM of your own and certainly reinforce with the captain/crew the extra assistance you requested at booking - they may not be aware of it.
One of the Ventura boats (Spectre? maybe somebody reading this knows) do offer a higher level of service - I've seen their DM's in the water helping people doff gear and re-board. Not sure if they dive Catalina though from there.
As you expand your diving, other places that I know of that do true Valet Service are:
Barefoot Divers on Roatan - really true valet diving as mentioned.
DiveBVI on Virgin Gorda, British Virgin Islands - they sat my friend down all week and brought her gear. Took it from her on every dive also.
Most of the better dive liveaboards offer that service also. Many will provide a DM free on every dive when asked.
I have a bad knee so I frequently remove my gear in the water and let them take it.
---------- Post added August 20th, 2014 at 10:56 AM ----------
Wonder what this op does to accomodate the truly disabled?
It's overall things. Handicapped compliant rooms, minimal steps on the property, hard paths between facilities. Once I've seen a boat backed up to the dock so they could use a carefully secured ramp to wheel several divers on board thru the wider open stern. Most of the dive crew has gone thru HSA compliant training. Divetech at Cobalt Coast (Grand Cayman) has a whole section on their website about it. Although oddly enough IIRC there were about 5-6 stairs from the shop down to the ramp leading to the dive dock there. They also board at a marina nearby so possibly they have a better setup there.