hey! i live on capitol hill, too, so i'm very familiar with all hills in the area.

i think 75-80 gear inches is too high, though. i'd go with something in the high 60s. dolface provided the link to figure out your gear inches from your chainring/cog ratio.

here's what i've got on my bikes:
bike one - 44t chainring and 17t cog (w/front brake)
bike two - 47t chainring and 18t cog (no handbrakes)

they work out to be pretty similar gear inches (~70). if i'm going up 24th ave after a long ride, sometimes i wish i geared lower. i feel like i'm mashing up the hills sometimes. but when i'm on flats or going downhill, sometimes i wish i geared higher. with one gear, you have to sacrifice one or the other.