We hired one for 8 weeks and drove coast to coast (well almost) in 2012. we used Cruise America and hired their 19ft (only two of us)
First up i would say they are great for being able to be on the 'road' for most of the day and not having to worry about food, beds etc.
If you are going near large cities they can be a pain in the a*se, as some cities do not allow RV parking in the main areas you are likely to want to visit in a large city. so if you can stay near public transport thats a big bonus - or squeeze push bikes in (some do rent them) that way you can park on the outer of the city and then make your way without the parking dramas
We had some serious problems with the black water and ended up returning the vehicle (actually the second or third vehicle) about 2 weeks before the end
I cant say that Cruise America went out of their way to help us, until i really turned it on then we got personalised service and to their credit they gave us remaining time money back, plus, expenses, inconvenience and some additional money
National Parks and State parks are well equiped for RVs (in fact seem to make their existence off having them there), most are reasonably priced and decent facilities, parks in general seem to deal with late night arrivals far better then they do here - most have a system that is clearly explained at reception - essentially money in an envelope pull up to either a nominated site or find your own
Woodalls have a great app that is similar in function to Wikicamps - allows to find camps before and mark them as well look on the road what camps are in your general area so that you can plan how far you might want to drive into the night.
We found on the days we were going A to B there were reasonable number of parks along the interstates (usually close to it, a bit noisy but easy to find and get back on your way again)
Happy to answer any other questions .. our trip is documented on our blog (link below) and if select tag USA 2012 you can trawl through that, if it doesnt mention the park, im pretty i have them recorded elsewhere if you are interested to know where we stayed
Overall despite the trouble we had (which really i think was probably just really bad luck) we had a blast and found it so easy to get around and do what we wanted to do, there were very few things we didnt get to because of the RV
Enjoy your travels, we just love the states and i hope that this has helped in some way.
E.
