In case you decide against the train/Metro combo, I had originally reserved with
http://www.romeshuttlelimousine.com/ before our flights changed to a much-earlier arrival. After doing much research, I found that they seemed to have the best rate, and were very responsive to my inquiries.
Also, when I asked the Westin Excelsior concierge for a family-friendly restaurant recommendation, he made a reservation for us at Le Fric. While the food and service was good, it seemed quite overpriced. This being our first dinner in Italy, we were caught offguard by the seemingly outrageous pain et coperte fee of 6 Euro per head, or 24 Euro for, as it was explained to us, bread (3 small slices, to be exact). This, on top of a hefty bill, shaded our experience. We soon realized this was commonplace for Italy. Oh, and the 10 Euro per small can of Coke still seems a bit steep!
For a delightful breakfast, go two blocks up Via Veneto to a right onto via Sardegna. There is a wonderful little Bar with cafe seating that is full of character and value! Again, the concierge can direct you. Don't expect a ton of personality from the hotel staff, however.
If you go to St. Peter's by Metro, be sure to look off to the left on one of the side streets for the green and yellow neon Pizza al taglio sign off Via di P.ta Angelica (via Ottaviano, the street from the Ottaviano metro, changes names). You will have some of the best pizza you've eaten, in countless varieties, for very little money!
We never felt unsafe in Rome, though, as always, be aware of your surroundings and take precautions against pickpockets. We found that we enjoyed the stroll from the hotel to the Barberini Metro. Be sure to say hello to my Lamborghini convertible in the showroom window at the top of the Metro stairs!