Molly, when you get squeaking with cantilever brakes, it's often a matter of getting the pad angles adjusted, correctly. Either that and the pads build up a glaze. I usually clean off the pads a bit with an abrasive or good cleaner when they get too much glaze. That helps. You should replace those pads on a regular basis, anyway.

On disc brakes, you can also get some really awful screeching. That's also a glaze building up on the rotors. Easy fix, though. I take some light sandpaper and rub the rotors, then make sure to wash off any sand that gets left.

Also, very much agree with Trek420 about being able to ride any kind of bike anywhere, at least to some extent. Your present bike may not be the best choice for a given riding situation, but your riding skills can overcome a lot of equipment shortcomings. Mostly, though, I'm a big believer on deciding what works for you and not what someone else says.