We returned last night from 4 amazing nights in Rome (2 nights Belgrade, 4 Rome, 3 Positano).
With about 5 days in the middle of the hot tourist season, we didn't even try to see everything that interested us. We picked our can't miss of standards (Palatine, Forum, Colosseum, Vatican, Catacombs, Pantheon, Spanish Steps, Trevi Fountain, Piazza Navona, the Capitolini Museum) and saved room other important things like simple wandering, cafe-sitting and gelato-sampling. We had an awesome, un-stressed time.
Navigating the train station and metro was simple - just follow the color-coded signs - although some of the metro labyrinth made me wonder if it wasn't just faster to walk above ground, but it did provide a break from the sun's rays. If you aren't using the Roma Pass, hold on to your ticket stub, because transit police occasionally check on exit. The bus was ok - a little hotter, but reliable. And by using the start run/end run times printed on the bus stop signs, you can approximate the schedule. Remember, getting off/on public transport is nothing short of Darwinian - the weak will be trampled by the strong - just dive in and be strong.
If you are traveling to Rome in the near future, please know that it will be oppressively hot and consider how comfortable you are with heat and sun as you plan your day. Bring a water bottle with you, drink constantly (because you will sweat constantly) and top it off when you pass one of the ample public water fountains, which look like a tap running out of the wall. Use sunscreen (I'd see people walking around lobster red and it made me so sad to think what that was going to do to their vacation). Discover the joys of linen (I bought super comfy linen pants from a street vendor near the Vatican for 12 e). Do your Colosseum/Forum visiting in the early morning. Consider a siesta in your a/c hotel room and a refreshing cool shower during the worst heat of the day.
The food was generally fantastic. The first restaurant we stumbled into was our favorite - in an alley between the Spanish Steps and Piazza del Popolo, Il Brillo Parlante. The bruschetta was addictive, as was the pasta l'amatriciana and the salada misto was fresh and lively. We ate here for lunch twice and sadly, never got past the primo course. Service was excellent, polite and our waiter volunteered an excellent wine at a lower price-point, too.
Finally, Two Things I Obsessed About Before That I Felt Very Silly About During My Trip:
1. Theft. I felt very safe at all times in Rome. After reading up on the net, I arrived in the city with my pacsafe bag and neck pouch, prepared to fend off professional pickpockets, baby-throwing gypsies and rose-pushing peddlers ("sona allergica!") at every corner. But boy, did I feel a little silly. Not that those things haven't happened to people and it's not important to be prudent, because it is - but I didn't experience any encounters of that sort. A simple no, wave of the hand and lack of eye-contact was all it took for us to send unwanted visitors on their way.
2. Attire. If you are really concerned with this, be assured that if you aren't wearing cut offs and t-shirts, you'll be better dressed than 90% of the tourists in Rome. And comfortable people are attractive people. There are denim, shorts, and sneakers EVERYWHERE. Wear what you'll be comfortable in 90+ degree heat in (my vote = linen!).
Rome is a gorgeous city, full of life and history and delicious food! Enjoy!