Glenn,
Now that we are retired, we are able to avoid travel during peak summer months, and therefore don't make reservations. We purchased our 2010 2551 last April and spent 4 weeks in Arizona where we took delivery, no reservations no problem. Then we took of in the fall for 6 weeks in 8 western states and only made reservations enroute to Missoula because we needed to have the generator repaired there. Now we are completing a 7 week trip to Arizona (escaping the winter weather at home in the Sierra Nevada), again no reservations and no problem. These trips are about 50/50 rv parks and state or fed campgrounds.
We love not having to plan and make reservations, allows us to go where and when we want, stay longer if we like it and move on if we don't.
This works very well for us in the western states, don't know about the rest of the country. And if we were forced to go during peak season to popular places then we would probably need to make reservations.
Bob