Camping

You can certainly go the camper route, and I've seen many campgrounds out on the edges of cities in Europe. You'll not have a secondary source of transportation--what we call Toads.

But the camper rentals are quite expensive and they're not quite the luxurious Class C's or Class D's we're used to having in the U.S. It might be cheaper to rent a compact car and stay in budget accommodations.

on two trips to Europe we have driven nearly 8000 kms through various countries ( 8 countries) in a smallish car ( similar to a toyota corrolla) and while it was good on the highways I could not think of anything more harrowing than driving anything much bigger than that on the roads in those countries.( anywhere near the smaller towns and cities)
Having driven motorhomes/campervans in Australia I take my hat off to those who drive them in Europe. a few weeks ago while in Germany we noticed heaps and heaps of motor homes mostly with Netherland plates ? mostly older couples.

The width of the smaller roads and parking etc in general is much much different than what I have ever experienced at home or in the USA.
I have found that GPS's ( we actually used two GPS simultaneously this year, for a test. Three female voices in the car at the same time !!!, wife my wife looking at the map) often don't discriminate between small width roads and larger roads so you can be sent down some 'impossible' roads at times.
we have enjoyed just using a car and finding accommodation in smaller pensions/ hotels etc. I realise that is not everyones cup of tea.

hope this helps.

Many thanks for your input and informative and enlightening responses, we do appreciate it.
While we've heard & thought about speed, traffic, tight/narrow roads, plus we don't know where were going!
Actually even considering a Rick Steve's tour for our first bout there, and at the very least, buying "Europe thru the Back Door" guide book.
Getting informed, making a plan, it's all part of the fun!
Much aloha, Vicki

See tips and links at http://www.ricksteves.com/travel-tips/sleeping-eating/camping. The recommended Europe by Van and Motorhome is a good read and geared toward first-timers.