That depends a little on what size boat you are talking about, what you intend to do with it (day sail, weekend trips, months long cruise
, live aboard), how much experience you have apart from the 101 course, that sort of thing.
If you don't have much experience and you're thinking of getting a boat in the 30' and over range and plan to do more than day sailing
, the 103 and 104 classes
might not be a bad idea. They'll give you hands-on time with a larger boat and introduce you to things you may not have had to deal with if you took the 101 on a small boat (marine heads, stoves, etc).
If you're wanting a smaller boat, say 23' or under, and you just want to do day sails
around home, the 101 class may be enough for you. If you don't have much experience, I'd recommend trying to find a place to rent boats from for a while first to get some sailing time under your belt, but that's just me.