Your pace is similar to my family's--we did our big European trip a few years ago with four kids (ages 18, 15, 12, and 4) through France, Italy, and Spain. using Eurailpasses. In retrospect, those countries were great choices for us, and I do not regret giving a miss to Germany, Switzerland, Austria, and the Netherlands, though I wish we'd been able to get to England and beyond. I also do not regret spending only a day or two in each city--I would get bored if I stayed longer in most of the places we visited.

Everyone in the family had a different wish list, and we packed a lot into two weeks, starting and ending in Paris. What worked for us:

* We tried to spend (at least) every other night in a hotel rather than sleep on the train every night.

* We alternated the bigger, more touristy spots with smaller, more manageable stops. e.g. We walked all over Barcelona, but then spent a day hanging out in Girona/Gerona, a very cool city that everyone loved.

* Mid-trip, we had a beach day on the Mediterranean coast. Even the hour-long boat ride on the Seine was a nice break when our feet were aching.

* We walked and walked and walked, taking public transportation only when absolutely necessary.

I'd say the highlights were Rome (hot hot hot in July) and of course Paris, where I heard more English than I do around here. The kids were captivated by Venice--and for the first time, I was able to see it as a magical place rather than as the ultimate tourist trap. We had to bypass Monaco (the kids looked at it longingly from the train) and the Italian lakes region for lack of time, and were not able to spend as much time in Spain as I would have liked. A side note: World Cup is next year, hosted by Germany, so best to avoid if traveling at the beginning of summer-- unless you have booked everything in advance.

My oldest started college the year after our trip, spent the following summer attending school in England, and then traveled everywhere in Europe for two months. Last summer he did volunteer work in Ghana, and now he's heading for Korea. Our European trip whetted his interest in travel, and he's determined to see the world before he's 25 (for whatever reason, he seems to think that it will be impossible to find time to travel once he finishes school and gets a real job.)

I say go for it--your kids are the perfect age to appreciate and enjoy the experience, and I hope your trip is as incredible as ours was (despite the occasional meltdown).

JoAnne in Silicon Valley, CA