Congrats Dwight! That is just super! I'm sure easily riding on past where you quit last time was a huge rush just knowing you were that much stronger.
I need to get out and do one of those some day-we just don't have many organized doubles around here to speak of. I'm just guessing that my time would be comparable to what you folks rode it in so it feels doable. If I use our December Centuries as a gauge (100 miles, 4000 ft of climbing in 5 hr 30 mins) and assume I'd go a little more moderate pace since it is 200 miles then that would put me at about the same time. It also looks like there is a touch more climbing in the back part than the front part.
Based on your experience (Curtis and Dwight), if someone were comfortably doing weekly centuries, would that be sufficient training or is there a need to throw in a century+ training ride a few weeks in advance. I've done 200 miles in a day but it was about half the climbing of Solvang-maybe half as much climbing. I've also done 160 miles in less than 8 hours but the conditions were perfect with even a little helping wind and only about 3000 ft of climbing. I'm not sure who was actually on the bike that day!
I think most of the organized double centuries are in the west. Having said that, you could have a brevet series near you (which reminds me I need to renew my RUSA membership). Your century times are better than mine. My training rides were a century in Jan, 1 in Feb, and a 95 mile ride the first week of March. I think you have the fitness for a 300k or double. It is important to remember to start eating early, and to continue eating. I took Hammer Enduralyte pills at every sag too. You pace yourself; I dont want to try for a 6 hour century pace, but stronger riders might. A lot is mental. You know 100 miles is about half way, so your goal is beyond that. You also have to be aware that at some point you will have to work thru a feeling that you are not on top of your game. Eat a gel, and push on. If you can find a ride partner that has some long distance experience that would be great.