Yeah, what you're talking about is definitely "lakes, bays, and sounds", and not open water, except on a day when the wind is either calm (which you don't want, for sailing) or offshore so you have a fairly flat sea.
That said, there's no reason why you can't learn, and enjoy, sailing on one. Most of sailing is done on lakes, bays, and sounds anyway.
If you want to sail off and onto the beach, you may want to pick a boat with a centerboard (which swivels upward around a pin) than a daggerboard (which has to be lifted straight up), and a rudder that will kick up if it scrapes bottom. This way, you can beach her with some speed and have less distance to pull her clear of the water or surf.