We try to make as few trips as possible, I try to limit it to one a day. Up until I moved back out to the San Juans I didn't own a car, the public transport system wasn't so bad down in Seattle (at least I knew it well enough to get wherever I needed to go in a reasonable amount of time). Because they had buses period up here I thought "Great! I can just use their system!" only to find out buses only run once an hour (with a lunch break) and have erratic routes that take 3+ hours to just go 20 miles. Not even going to touch the ferries.
Luckily I live close enough to work that I can walk if I have to, and when the weather isn't cruddy I'll pick a bike up. Just sucks when we have to head into the next town for anything outside of groceries or hardware store stuff ($10-$15 in gas for each trip). I'd kill for a local store where I could pick up some freaking underpants and socks that isn't a touristy boutique or thrift shop (ew)