Some of you guys are either over-thinking this, or I'm missing out on a whole lot! All of my bikes have 9-speed Shimano groups, with 50-34, 52-39, 52-39-30 and 50-34-24. They all work fine for me. The triples are on my touring bikes on which I might be carrying heavier loads. The compact double is on my cyclocross bike, and I'm about to put another compact on sport touring frame that I recently picked up.

The only gearing combinations that didn't work for me were a single-speed that just about destroyed my knees, and a 1x9 with 42 chainring and 12-27 cassette. On the 1x9, I found that I was actually having to shift more often than with my doubles and triples. There are a lot of hills around here, and I was pretty much using the entire range of the cassette on almost every ride. However, with my doubles or triples, I often can simply shift the big ring on hills without shifting up and down the cogs on the cassette.