There isn't anything wrong with a soundbar. Especially for a bedroom. If this was for a living room or entertainment room then ya, maybe you could argue that a 5.1 or 7.1 surround system is better.
I live in a condo, and while my living room is large, i have vaulted ceilings(like 20 feet) and a surround system just wouldn't work. so i'm looking at HT-CT100 | Component Home Theater System HT-CT100 | Sony | SonyStyle USA. I can hook up my ps3 hdmi and my directv hdmi cables to this and simply run it to the TV.
I may look into something with a wireless sub, but really, for a room the size you're describing this is really all you need.