As a general rule I play with units at +2, trees full on and using views 1 for turn replays and planning stealthy routes for my units ( I actually "walk" the route they're gonna), 3 and/or 4 for order phases and 6/7 for developing a general stategy (usually in the first few turns of a game).
Does any body else use the overhead views ? I've rarely heard mention of people using them in the 5 months I've been lurking !