Nice report and pics.
This was our first tandem century; we did it in '07 and although the weather was similar to what you had, we had overcast skies. Still, shorts and short-sleeved jerseys in February are a novelty.
Somewhere, on a road that looks like GF Dr., cgallagh said to me, "Gawd, I'm tired, I don't know how much longer I can do this." A voice behind us said, "Don't look now, but you're pulling a few people." We looked back and sure enough, we were pulling at least 30 cyclists. That was enough incentive for us to kick it up and finish strong.
It's a long way for us to travel but on a day such as you had, a ton of fun and a good excuse to leave the NorCal gloom.