What range of gears do you use in your commute?

I just ordered a 2009 Breezer Uptown 8 from my LBS (orange20bikes.com), after trying out the cheaper EX model at the shop. This bike comes with a Nexus 8 speed hub, 38 tooth chainring and 18 tooth rear cog. It has 170 mm cranks (which may be too long for me? I'm 5'6") and 26" x 1.75" tires.

According to Sheldon Brown's calculator (http://www.sheldonbrown.com/gears/internal.html), this set up provides a gain ratio of 2.1 in the low gear, up to 6.6 in the high gear. Gear inches are 29 to 89. This means I should be able to go as slow as 5 mph at 60 rpm in low gear, and as fast as 25 mph at 100 rpm in high gear, according to the calculator.

I'm actually considering switching to a 20 or 22 tooth rear cog, for lower gearing on steeper hills. But perhaps the current gearing is fine. I rarely feel the need to go faster than 15 mph, even on downhills; I'll just coast. I'm currently riding an old Schwinn Breeze 3-speed on my 3.5 mile commute (well, it's been 11 miles each way this month, but that's only temporary), with a few 4 to 6% grades about a block long.

What gears do you use the most on your commute? Do you usually wish for a lower gear for the hills or starting off, or for a higher gear on the downhills and with a tail-wind?