I have a little wristwatch GPS (Garmin). I take it when I travel all the time.

It's worked great everywhere I've gone in North America and Central America. Sometimes takes a while to calibrate when I first arrive in a new city...

(It's obviously not the full-fledged device with mapping and directions and all that a lot of folks here have. Its main purpose is to show distance traveled and instant or average pace, and then you can hook it up to a computer to display graphs and such. I love it for training runs in strange locales.)