See if you can get 2 rooms on cash and points using Starwood. I started doing this overseas with the children due to the same issues.

I think Marriott has a policy where children up to certain age (can't remember the number) can stay with adults/their parents in their room. Can anyone find to link to this info on the new web site? This maybe helpful if you redeem on points so it's included in the room.

Wait, the Courtyard in Rome does allows 3 people legit; it just costs much more! It maybe cheaper to book (w/ cash) 2 rooms or 1 room w/ points and another with cash. Look at the breakfast costs as well when you decide.

Or as someone else suggested, get a small local apartment or European style hotel room. If you are just looking for a clean, comfortable, relatively close to attractions/public transport options focusing most of the time on seeing the sights, then there are plenty of choices in the large Western European cities; no need to shell out for US brand name hotels.

I wouldn't recommend the sneak 3rd person approach; usually all foreigners have to provide passport details upon check in. The front desk staff overseas are more attentive about these things than in the US/CAN. For example, I have only been asked for a business card for my corporate rate ever overseas.