I'm another fan of bike paths. They can be crowded, but so are the roads they usually help you avoid and a 'bike path' incident will be less damaging then a road (read 'car') incident. Our local bike coalition is always fighting for more money for bike paths and lanes and often have to counter the argument that they aren't used that much, so I encourage their use whenever possible so they are used.

As for alerting other users I agree that early warning is best. A combination of a bell ring and "on your left" seems to work. Sometimes when you just say "on your left" they think you're pointing out something on that side of the road.