I carried my soul home, dusted it off, and went out for a 2 hour ride on my own. It was great - just not very social.
I'm not going to say anything negative about the other riders. In fact, I know several of them and they are OK folks. They just had different objectives for today's ride than I did. I averaged over 15 MPH for the portion that I rode, but they dropped me like a stone so I'm thinking they were riding 18 - 20+. Another rider suggested this was a group that I should try riding with but I'm not up to that pace.
Incidentally, there is a group in St Louis for slowish riders. It's called the "Turtles." They don't ride big hills and they never drop anybody. I've ridden with them, but they are too slow for me. There's also a "Turbo Turtles."