Originally Posted by pinniped

We've done a month in Europe with 5 total. Also gone back for a couple of other trips in the 2-week range with 4 or 5 total. We did a mix of Booking.com and standard hotel awards. The challenge is that in some cities, most hotels are max-2-per-room for legitimate fire code reasons (e.g., tiny rooms - you wouldn't want 3 in them). So a little 2-bedroom flat ends up being a lot more enjoyable. Booking.com is a good spot for these - probably better than VRBO.com in some cities. (We chose not to get into the AirBnB thing, although that may be an option for some.)

We always rent a car. Our trips often involve smaller towns, visiting friends in different countries, etc. I always do the due diligence and look to see if trains, cheap flights, etc. would reduce the need for a car, but it rarely does. Obviously if we were just going city-to-city, the hassle of parking and driving might not be worth it.

We almost always redeem Y seats. J seats for kids seems like a waste, and finding 5 together in the summer is going to be a tough task anyway. A few years ago, we got all of our seats together on EI, a decent airline if you don't hold any relevant elite statuses. The last couple trips we've gotten 4-5 together on AA via secondary cities. Even in the summer, when MAD, CDG, etc. are booked solid and LHR has lots of junk fees, look at the German cities with an AB connection. Last year, with only a few weeks' advance planning, we saw some options here and ended up on an ORD-DUS flight that wasn't 100% full. All awards, all ended up in MCE.

The lesson we learned over time is to *not* move from city to city as much as we did traveling without kids. The act of travel has high overhead, even just loading/unloading a van, so we learned that 5 people trying to hit a new town every day was a little too much. If you know you *have* to do some rapid-fire travel for whatever reason, follow it with a few days in one place that you know the kids will enjoy.