Rome is a great place, but the sheer volume of tourists can take away from the ambiance sometimes, so February is a great time to go. Rome has a huge difference of price between premises immediately beside the main monuments and the rest of the city, more so than any other place. There is excellent value to be had, but not if you buy from the stalls outside the monuments which can be outrageously expensive. As for etiquette, don't mark yourself as an unsophisticated tourist by ordering a cappuccino in the afternoon or even worse after your dinner. Enjoy.