I've only been out with the SPIN Idaho group once, but I really enjoyed my time. I met Michael, one of the "ringleaders" for this group, and rode with about twenty other like-minded roadies on a windy day in Kuna, Idaho. Of course, the more I ride in Idaho, the more I realize that Idaho is not really ever going to be wind-free. I just wish it wouldn't be a headwind in any direction.
I digress: The group is top-notch, there are no drops, and the skill level varies. Michael rides his recumbent and the rest ride a hodge-podge of roadies, hybrids, etc. I was happy to ride and can't wait for the next opportunity. I recommend SPIN Idaho if you're in the area, new to the area, or just looking to ride with a bunch of good folks.
The group keeps a great calendar on its website, including maps and a list of upcoming rides. Enjoy the ride!