I have never been much for group bike rides. I tend to phase out during rides and like cruising along with my thoughts for an hour at 12 miles per hour. Moving in a crowd takes a higher level of concentration, but also provides a bit of safety as a motorist might not notice one rider, but should notice a dozen.
I did enjoy the ride organized by the Arvada Triathlon Club. It was a low key get to know each other ride and we cruised a little over 11 miles in around an hour, including stops to regroup. I learned some new hand signals. I always knew left, right and debris on road, but I was introduced to slow and stop as well.
I am assuming the speeds will pick up as the getting to know each other phase passes, but it will still be fun to ride with people I know. I occasionally ride with the neighbors, but those tend to be longer (20-25 mile) rides that last 1.5 to 2 hours.