We usually stay in one place at least a week. You can often get a break on a hotel or an apartment with a stay that long.

My suggestion is to pick a major city, London (not this year because of the Olympics), Paris, Rome, Berlin, Munich, or wherever they have a lot of what you want to see, and spend your whole time there, with perhaps a few day trips. My choice would be Paris, which has everything. The modernista architecture in Barcelona might be good for you.

I like the idea of one major city and I’d base in Paris even though I’m not a huge fan of the city. While you could easily spend the whole time there, just seeing the sights and taking day trips, you’ve got a whole lot vastly diverse options nearby. London is just over 2 hours by train, Brugges (quaint, medieval Belgium) is about 2 1/2 hours. D-day history and other interesting places are 4 hours away in Normandy. Strassburg is a nearby and Amsterdam is easy to reach. If you want to go farther afield, Paris is a transportation hub so easy to find flights or overnight trains to almost any major city in Europe.

An open jaw flight (use the multi-city option when searching) into Paris and out of Frankfurt (or vise versatile) would allow a couple of days in the Rhine Valley (take one of the day cruises and stay overnight along the Rhine) and the rest of the time in and around Paris. You could get a huge variety “taste of Europe” in a very short time.

My latest plan for a trip about that length is a few things I’ve missed or want to re-visit in Paris, Mont St. Michael, a day or two in Brugges and a leisurely re-visit of the Rhine valley.

I agree that Paris is a very workable option, esp with an open-jaw flight. As Oldlady says, it would be easy to stick London in there, I’ve done a 10 day Paris/London trip.