I agree with Machka, there are times when you have to back down on the cadence or burn your cardio system out. We have a lot of 10-12% grades out here in northern calif that are several miles long, and I like the 21" low gear I have with the mtn crankset (24-30). Just putt up the hill at a nice sightseeing pace.

The Vetta V100A has an altimeter and does a really nice job. It will compute the current altitude, max alt, total gain for the ride and % grade as you are climbing or descending. I am often suprised to find I have several thousand feet total gain on a couple hour ride that did not even involve any major climbs, just a lot of rolling hills and smaller 3-500' grades adds up. It is also wireless and has temp which I find interesting if not particularly enlightening.