Suunto is the way to go...
I have been using the 2 years old modell, Vector that
has altimeter, barometer,compass etc...
It has been proven in use that the altimeter is very
accurate (if you remember to calibrate it...). It goes
up 6000m if I remember correctly. In the new modells
it should go up to 9000m if im not wrong.
Also the electronical compass is the most accurate on the
market, but it has to be calibrated quite often too.
Oh, and it has a watch too...