I completed my first organized ride yesterday, a "25 mile" one which was actually about 27 miles. Overall, it went just fine. Registration was available over the course of 3 hours, so everyone started at their own time... whenever. It was very relaxed.
My boyfriend and I rode together along the scenic, country route which took us along various 45-50 mph roads with little traffic. The route was easily marked with big yellow spray-painted arrows on the road, plus, we had a map.
People seem to drive differently in the country than in the city. I never felt like the cars passing us were too close or that the drivers were doing anything stupid on the road. Of course, it was a Sunday morning...
There are three things, however, that I learned yesterday:
1. I HATE :irritated 'rolling' hills. They just keep coming... over & over again. Just when you think you can get a break, there's another hill on the horizon. I learned to deal with them by gaining as much speed on downhills as I could, and using that to carry myself up most of the next hill. Hey, at least I kept riding and never had to walk those darn hills.
2. I LOVE

my new Camelbak. It's great to have easy access to water, especially on a hot summer day.
3. I NEED to put in more time on my bike if I expect to successfully complete the 50-mile ride I plan to do in a couple of weeks... otherwise, my butt will absolutely hate me.

(I didn't get as much saddle time this past week as I wanted.)
The only mechanical problem I had was when my chain jumped off once while I was moving into a lower gear. It's a weird feeling to be pedaling and suddenly have no gears. It was a quick fix at the side of the road.
We had ice cream (and bananas, orange drink, etc.) at the halfway point of the ride. That ice cream was the best I've tasted in a long time!
All in all, it was a fun experience and I would do it again. BTW, I bought some Continental Town & Country slicks on Saturday for my MTB. I really think those tires made a difference in my ride. My boyfriend rode his road bike, a Specialized Allez. Someday, I may look into getting a road bike.