Just got back from a BOS AMS FCO trip on NW/KLM. The seats are nothing special and the plane was packed. two movies were shown. Teenagers would have liked them. I didn't watch. Book and CD player does it for me. Meal was fine but unremarkable. I ate some (my usual habit). Heinekins were cold, so I had a few. The flight goes quickly enough. If you have status with NW you may be able to get row 22 center.
We worried about the long layover in AMS but it actually gives you plently of time to visit the city. Again I think the teenagers would like it. AMS is very different and while there won't be tulips the red-light district is there but at that hour there won't be much happening. (probably a winning proposition considering the teenagers.)
We had never been to AMS so we checked our carry-ons in a terminal locker for 4 euros and took the train downtown and walked around the city looking at the canals and architecture for a couple hours. We watched the parents pedalling their kids to school on the back of their bikes. Had a coffee and apple strudel then took the train back to AMS and made it with plently of time to spare. It is only a 20 minute or so train trip. You can buy a round trip return ticket at the airport (leaves from platform 3?) for 6 euros or so, then check out the downtown platform (maybe 13 or 14) and schedule to see when you have to be back to the rail station.
It was dark at 8 am when we arrived in AMS and it didn't get light until 10 am or so. Not too much traffic, but nice for having little sleep.
Try this link
http://www.flyertalk.com/forum/Forum28/HTML/002028.html
http://www.flyertalk.com/forum/Forum35/HTML/007753.html
This short break had the effect of substantially reducing our jet lag in FCO. Usually, my wife is asleep by 7pm on our first day in Europe, no matter how hard I push her to stay awake, but we stayed up til past 11 pm walking around the piazzas in Roma eating gelato and panini and slept soundly that night, waking the next day ready for sightseeing.
The KLM flight from AMS to FCO was easy but we were in exit rows with plenty of legroom. The plane had 3-3 seating which has caused complaints on the KLM forum. Had some kind of cheese sandwich, coleslaw, crackers, and a brownie. Again I ate some. No entertainment. Coming back FCO to AMS, the plane had 2-3 seting, MUCH more room. very nice product. (same breakfast) The NW AMS BOS was same as before. For $350 earning 20,000 miles, who can argue? (Your miles may vary.)