I've got by on 10 and now 12 gears for years.
All the additional number of gears does is allow you to have the same spread with closer ratios or a greater spread.
I run a 48/36 front, with a 12 to 28 rear (6 speed) and have found it to be fine.
I've never had to get off on a hill, but if bottom isn't low enough think I would get off and walk as it would be just as fast as pedalling.
Oh, and I use friction shifters (Campag) as they are the easiest things to adjust and fix on tour.