For Kumoricon, it takes me around three to three and a half hours. Depending on traffic and which route I choose.
If its a nice day, ill drive up the coastline, through Newport and Lincoln City. If its not, Ill take 126 to Eugene, and go up that way.
It took me about eight hours to go to Sakuracon. Including rest breaks and a lunch break. The weather was terrible, and I went alone, too. Didn't have anyone to carpool with back then, lol. Plus, my friend who was supposed to go cancelled at the last minute, becauses his work called him in, even though he had the time off.
I live in Southern Oregon, so, yeah. However, I have done the ride to Portland so many times, it just flies right by, now.
As for how far I would go for a con. I would have no limits. If I wanted to go, I would go. Heck, I almost made it to A-kon two years ago, and almost to AX last year. Wish I hadn't missed AX last year. Hara Tetsuo was there, and I really wanted to meet him, even though he wasn't there as a guest, and he hosted a panel of sorts. Not sure, but a friend of mine that lives in Oceanside went, and another friend that lives in San Diego.