I say 4 foot because sailing the gulf coast of the US over 4 foot resticts most of our favorite places to anchor. Having only once had the pleasure of the Bahamas I found a few places we could not enter because dads' Hunter drew to much. So that is where the 4 foot idea comes from.
When we (wife and I) think about sailing we look at ocean crossing as a needed evil to get to the cool places. We want to be able to duck in to places others can't.
My personal experience with center board,dagger board, swing keel is all in protected waters and I do not find sufficient writings on there use as true bluewater boats. (I am Sure you guys can give the names of some books I just hadn't really found enough info.)
I am comfortable in close quarters in a 33 footer. A decent amount of experience. Much larger than that and well you know married coouple in their late 40's, slow reflexes and all.
Thoughts on multi hull vessels. Well sailing flat to me is a very uneasy feeling. Tried it a couple of times with friends and it just isn't me.
To anyone jumping in late to this thread, please disregard my earlier ramblings. Obviously I forgot to take my Midol this Am.