deepstops:Truk Aggressor II - outstanding in every way possible.
A boat I would not go on is the Solmar V - still no nitrox last time I checked, . I wouldn't think of doing five dives a day without nitrox. And besides, the Nautilus Explorer is doing the Socorros now. I haven't been on it but it has a stellar rep.
I'm going to Cocos Islands in 2006 w/ one of the Sea Hunter boats. That promises to set a new standard for me.
I've been on the Solmar, and it is a superb trip. I'm not nitrox certified so I wouldn't have had the same concerns as you tho. In any case, the five dives a day argument didn't apply - I think because of the very abundant shark life around, we didn't do any night dives! This might be different on the Sea of Cortez trip, I went to Socorro.
We did have a very entertaining evening wathing loads of dolphins and sharks feeding just off the side of the boat - the fish were attracted to the boat lights so they were having a feeding frenzy there - made me feel quite happy not to be in the water ;-) The most surprising thing for me to see was how much faster the dolphins were than the sharks at catching dinner - amazing!