I can't help with November since I've only been to the Bahamas in the summer but you should be ok since it's after the hurricane season.
Liveaboards from Nassau are limited. One option would be
Blackbeards,
Cat Ppalu or
Aquacat, all owned by the same company. Different levels of service based on the price.
Seadragon also looks like they have some charters out of Nassau in Nov. Not sure if they're private or public.
Another Bahamas option might be
Juliet but she sails out of Miami.
There's no Aggressor boat in the Bahamas afaik and the Caribbean Explorer 1 is retiring Nov. 1st. - it's out of Exuma anyway - and CEX2 won't be sailing out of there until Mar 2009. There's no Hughes boat (Dancer Fleet) in the Bahamas either.
And the Nekton boats are both doing the
PR/St. Croix trips in November out of San Juan
PR. In the summer when they do the Bahamas trips, they leave from Ft. Lauderdale. We did Cay Sal (south Bahamas) a couple years ago, it was a good trip to see big stuff - turtles, sharks, rays barracuda etc. on just about every dive.
I would contact any liveaboards you're interested in soon also as they may be all booked for November by now. Although with the price of airline tickets, maybe not...