So. We've not gone crazy yet, and we can say: Yes, it's totally possible to travel with four kids and have tremendous amounts of fun. Even if one of your kids has ADHD (and we're suspecting another case after this trip but we shall see about that). Even if you have a teething, mostly miserable newly-minted toddler with you. Even if one of your kids screams for his Oma at the top of his lungs whenever something goes against his wishes.
We had a great time and we will do it again. To alleviate the troubles with the hotel rooms -- there were none, really, but we were very lucky to get a one-bedroom suite with Priceline for our last night in New York City -- I found a great website: Six Suitcase Travel. Here one can find lists with hotels that accommodate six per room(s). I wished I had know of this site before we started out. The single most important lesson of this trip is that you do not want to have a tiny closet-sized room in a dingy hotel for those first jet-lagged nights. Even if it's in a great location and at a great prize.
Speaking of six suitcases: The other great result was that traveling lightly was the best idea we ever had. We traveled with two suitcases - one for our stuff and one for our purchases on the way. Once in DC, we got two more backpacks out of storage and added a duffel bag - so now we're up to five suitcases. But that's only for the trip back and because we carry so much stuff home. (Mostly clothing, as kids' clothes are cheaper in the US). But the system with only two T-shirts and two pairs of pants, and one sweater worked great. It helped that we didn't need any jackets. I'm refining my packing system, though: Instead of giving everybody a packing cube for their own clothes, I will assign cubes to types of clothing: One for underwear and socks, one for T-shirts, and so on. We had to unpack all the cubes anyway and it made laundry more difficult.
But I'm babbling. We're in NYC and it's raining, the baby is taking a nap and the boys are off with Doug for last minute (toy) purchases. Here are some impressions from our trip - you can find more in my Flickr stream (link on the sidebar).
More once we're actually home!