I did a loop out of Livermore that included Del Puerto Canyon last year. It was about 105 - 110 miles, in January, so it was relatively early in the year for a century. It wasn't bad at all. I don't think the climbs in DP Canyon are nearly as long as Mines - I only remember one tough part that was very short.
I'm not just shining you on.
Look at my BJournal for stats on what I did - I would have called it Del Puerto canyon ride or Resolution century or something like that.
The Hamilton route would be a great one.