I will second that the CB is mostly static now-a-days. Sometimes you hear some truckers talking to each other. I thought it would be nice when camping somewhere, but it never got used that way.
Only once have I picked up state broadcast road warnings (ch 19) which told me which lane I wanted to be in on the Interstate in the traffic jam ahead. This meant I did not have to change lanes in heavy traffic, which is great for truckers and RVrs alike.
Only once have I run into another RVr on the CB. Some Class-A who had his stairs still out. I radio'd, he answered, and that was that.
I since removed the CB after listing to some Trucker curse and yell at me because I did not launch myself off the highway so he could continue at 80+ MPH. I figure if I can't hear them, they can't ruin my day :)
For emergency use you can pickup a handheld HAM radio (although license is require to broadcast, I doubt you would get in trouble if it were an emergency)