The uphill climbs are better with lower gears and higher spinning rates. The thing to watch for is knee injuries if you don't down shift. The injuries won't appear immediately, but if you keep stressing it, the pain will show up.

Therefore one gear won't do it all. Some inclines are short and some are long with switchbacks and lasting for miles. Also to take the pressure off your cardio system and legs, you can try to traverse the uphills, especially the longer ones. Obviously with a narrow bike path, a rider cannot really traverse (zig zag) up a hill very well. But on those lonely country roads, its possible. By traverse, I mean like downhill skiing, but only going uphill on the bike.

There's an ebb and flow of energy when you ride long distances or at high output. Going uphill just makes it more noticeable. Sometimes when I just want to give up and stop for a rest, I will resort to traversing to "cheat" my way up.