Make a reservation? Or no?

No problem at all. That's the only way to do it as far as I'm concerned. I wouldn't even be overly concerned about the cities at that time of year, but having a reservation might save a bit of time if the cities are new to you and you don't know the areas where plenty of things are available. I can't speak to Vienna, since I have little experience there.

In May you shouldn't have problems outside the cities. In the cities it will certainly save you valuable travel time and a particular advantage will be to inquire and plan on parking. I think you will want to leave the car outside London and will need to leave it outside Venice.

Agree with Ed unless you are needing a triple or quad.

Thank you for saying that! We ARE trying for quads, so I will keep that in mind. Maybe worry about cities and weekends, and "settle" for doubles in between?

Melody, My opinion on the subject is slightly different. May is considered "spring shoulder season" and it could be busy in Europe. At that time of year, you should be able to find a room if you're flexible in terms of location and price. I typically travel in either the spring or fall "shoulder seasons" and always pre-book my accommodations! That way I have a choice of which part of the cities I'll be staying, facilities at the Hotel and of course price range. During my travels, I've seen numerous examples of problems in finding accommodation. One example was a pair of young ladies who arrived late in the afternoon in Siena and couldn't find a place to stay. I rang up several locations, but no one had any vacancies (including the Convent). Their solution to the problem was to get a bottle of wine and sleep on the street! That's where "flexibility" works, as they could have travelled to a nearby town and probably found something. Happy travels!

Ouch! The quad business might throw in a slightly different wrinkle, but maybe not. You already said you were going to make reservations for the larger cities. Good, you've got that angle covered. But I'd bet I could go to any big place and, without even going to the TI, and find a quad or a couple of adjacent doubles in a heartbeat. Both London and Paris were virtually deserted during the fall shoulder season a couple of months ago. The hotels I stayed in were at about two/thirds occupancy at six or seven in the evening - - when I usually have to show up by mid-afternoon to get a room. The economy stinks. I was in the UK and the RoI during the spring shoulder season and the B&Bs were giving huge discounts just because somebody knocked on the door. The economy stinks. Ken probably has a valid point for the small 'hotspots', the Sienas and Colmars, but I'd bet that if those ladies had wheels, they could have driven fifteen minutes down the road, booked a room, and been back in Siena in time for supper and evening wandering. My problem with pre-booking is that it puts you on a stinking schedule. You can't take detours, you can't spend an extra night at someplace that you find is really neat. And you can't haul tail when a place is less than anticipated. Maybe that's what you need to do when most travel is by public transportation, but Melody's idea of driving obviates a whole batch of problems. I'll defer to somebody else with more recent experience on traveling with a mob, but years ago when I was chauffering my herd in a booming economy we never had a problem by not booking ahead.....and only the short kid got pneuomonia from a couple of nights on the park benches.

If you travel outside of high season, you shouldn't have a problem even if you are traveling as a family. The key here is how flexible are you regarding accomodations? If you won't be happy with a wide assortment of accomodations, you may want to book ahead. If clean and quiet are your only requirements, there will be plenty to choose from. We have traveled in Sept., Oct., and Nov. as a family of five sans reservations except for immediately after arrival (so I don't have to worry about it while jetlagged) and immediately before departure (because at that point my itinerary is fixed anyway). I prepare a list of places/phone numbers for each projected stop (from travel books and/or tripadvisor.com). I call in the morning before I need a place. At times I have to call more than one place but I have yet to go homeless.

We do this all the time. Before we leave the US we book a hotel for our first night in and last night out but other than that we wing it. Doing this gives us greater flexibilty of shortening on lengthening a stay in any place we visit; we are not tied to "having to get somewhere" because of a hotel reservation. Since you will have a car you'll have the flexibility of finding hotels in a wide geographic area but still close enough to your destinations. For example: We traveled in Italy and wanted to go to Rome but we know Rome's traffic is scary beyond belief. We looked on a map and drove in to Orte which is about a 30-40 minute train ride from Rome. Got a nice hotel, actually a suite for a very good price, parked the car in their underground parking and took the train into Rome every day. We have done this in Spain, Switzerland and France too. Buon Viaggio!

I wonder how much driving you are going to be doing. How do you plan to get between the areas you are visiting? You may be looking at thousands of miles of driving, which may make it hard to plan in advance where you are likely to be. If you sketch out a tentative (but flexible) itinerary, we might be able to give you more specific advice.