I live east of Kent near Covington along the Soos creek trail, and commute down into the Kent valley every day. I do fine with 8 speeds, its the gear range that counts.
26 to 80 gear inches is high enough for how fast I ride, and will get me up any hill I couldn't walk as fast. or faster than I could ride with lower gearing. James st heading east is a mile long 10%+ grade that's no problem. The abandoned section of road heading west out of the Soos creek valley is 14%+ and even when my mountain bike had 3 X 6 gearing it was a 50/50 chance I would have to stop and walk if I hit a rock or bump wrong.
I don't feel limited by My gearing, Saturday I rode south on the Soos creek trail to Covington, east on Kent Kangly road to Maple Valley, south on 169 to Black Diamond, west on Green valley rd to Auburn, north on the Green river trail to Southcenter, north on the river trail to Georgetown, Airport way to downtown Seattle, east on I-90 to Bellevue, south on the lake washington loop to Renton, east on the Cedar river trail to fairwood, and finally south on 140th to home. 83 miles.