I don't know about everyone else with automatic transmissions, but we go down to about 40 or so on bigger passes.  We've had manual transmissions on other Vanagons and I really don't think the automatic is that much slower on hills.  I know it's a lot faster in regular traffic situations.  We go down to about 40 on Cuestra grade here in San Luis Obispo, CA area, as well as most hills of any size.  What was surprising to me is that the last time we came back from Fresno on Highway 41 I think it is, there were two full size pickups behind me pulling something like tent trailers and they couldn't get around me when the passing lanes came up, and believe me I was bogged down to around 40-45 on most hilly areas of that road.

Sharon & Bob Mendonca
88 Westy
88 Vanagon GL