Just have the same good time that you would with one of your girlfriends. Give and take, laugh and get awestruck (stricken?), and just enjoy yourself.

Like you wrote yourself, enjoy your life while you have it and let him enjoy his too.

I wish someone had given me advice when I first traveled with a new boyfriend, maybe I would have been wiser.

I've done it and I am still with him 3 years later! Make sure you both take a step back and relax on the trip. Getting all picky about what you see and don't see or miss will be stressful so take sometime out on the trip to do a few separate things even if for 15 minutes you wander a few shops while he has a coffee. I am lucky my partner is very laid back and is up for seeing anything as its new to him.

what happens on this trip is indicative of your joint future together...if he makes you feel that he's doing you a favor when deferring to your wishes....just say goodbye at the usa airport.....keep your own money, passport, etc. (in case) and go with the italian flow and have a good time...