I would agree that living aboard in a marina and essentially having a floating apartment is very different from passagemaking. It certainly would affect what kind of boat you would decide to purchase, because the kind of boat I would personally get for living aboard in a sheltered marina and going out for fair-weather daysails or 100 mile weekenders in coastal or sheltered waters is about the exact opposite of what I have in fact just bought for extended cruising.
The Voyager's Handbook is excellent: so is Changing Courses by Donna Cantrell and Book Template
by Annie Hill.
But "living on a boat" and "sailing around while living on a boat" are really two different, if intersecting, lifestyles. The first one is mostly about creature comforts and the second is more about focusing on the boat as a means of getting safely from place to place with a modicum of independence from shore. This means (generally) fewer appliances and more equipment to power those that remain. If you have 60 or even 30 amps at your disposal at a dock on an "as-needed" basis, you don't need the same gear as someone on a mooring, for instance.
You can also get away with coastal class cruisers like Catalinas, Beneteaus, and even Hunters. A Nonsuch 33 is a shortish boat with vast areas of volume down below, thanks to the rarely seen cat rig. They make admirable liveaboards and decent coastal cruisers, if you don't mind not pointing so high.
Certainly a catamaran would make an excellent choice here, as they have bags of brightly lit space...but you'll want a mooring (cats don't fit a lot of docking situations) and you'll need a way to make power for the boat on that mooring.
But if you want to start as a dock-bound liveaboard and eventually move into a full-blown cruiser lifestyle, even just to the Caribbean, that will take a rather different boat. Beth Leonard's book is a good introduction to the costs and compromises aspects of this sort of life.
Discuss it with your wife. She, relatively unusually, is the driving force here, both in sailing experience and in having already a taste for living aboard. In my experience, this is fairly rare, and if you find that you can live in a 35 x 12 foot space (which is not hard in South Carolina due to the 11 months a year of pleasant to hot weather, and the one month of what we more northerly types call "launch weather"), then you should do well. It might involve buying one boat for a few years, and then buying a quite different one later if you decide to sail away on extended cruising.