I live in the SF Bay area, the peninsula, so lots of great hills everywhere.

My concern is that it seems like none of my friends who are great bikers do short rides, but an 8 miler with 1,300 or 1,400 feet of climbing seems like a great workout to me and very efficient time wise!

Also, I find it hard to motivate enough to ride fast on a flat ride, whereas a hill forces you to work!