Ok, I guess I'm not quite done with this...
After reading more on the deep cycle batteries and going through Don Casey's book, I have further questions:
I will be using the house battery for the usual day sail requirements and occasional weekend overnight (anchor lights, water pump and eventually car stereo) in South Florida.
Since my motoring time is very short, I am worried I won't be recharging the battery enough between overnights (I currently do not have a way to chahrge the batteries at the dock). I do not know my alternator's capacity but will check on it later on. (Atomic 4, on a 30' O'day).
So, should I look into other types of batteries? I'm looking at the Dual Purpose batteries sold at WM.
Also, is an AGM for house ok if I have a wet cell Starting battery? I'm thinking not but I want to make sure as many batteries I see advertised seem to be AGM.