I'd say NO on the Shih-tzu... my advisor has one, and I end up dog-sitting it every single time he goes away for a few days (how I love being a grad student slave). That dog is the most high-maintenance animal I've ever known. My advisor tells me it's because the dog was a lapdog for emperors for thousands of years, so it's bred into him to be treated like a king.
I guess the dog was treated badly in his previous home (he was rescued from the pound), because he's terribly insecure and must be basically touching a human at all times. Even at night, he crawls up on the bed, slowly, until he's practically sitting on my chest or in my ear (where he promptly licks his chops all night, which drives me CRAAAAAZY). He doesn't bark too much, I'll give him that.
So, I recommend NOT getting a shih-tzu, though of course, you could find a perfectly quiet and obedient one. You just never know.
Maybe the best thing to do would find someone who already owns a dog and wants to get rid of it, so that you already know the dog's disposition. People are always moving and wanting to schluff off their animals
so I bet you could find one on Craigslist or something?