I know you can never see everythinmg you read about or want to see ...but what as a first time are must do's in Rome ?
Buy the Rick Steves Rome Book and follow his itinerary
Spend one entire day wandering from the Coloseum, through the Forum, to Piazza Navona, and on past the Pantheon to the Trevi to the Spanish Steps. There are many neighborhood churches which all hold wonderful surprises inside, fountains, sculpture, small tratorias, and plenty of gelato and water all along the way.
Spend a second day at the Vatican.
I would add the Borghese Gallerie to your list of things to do. It's outstanding.
Sally has the right idea. I would do the same.
Greg
If you have a few days, I would definitely go to Ostia Antica. It is just outside Rome, but very easy to get to. You take a subway and transfer to a train, and you're there in about 1/2 hour. Ostia is a ruined Roman town. The place is immense. My wife and I got there at around 10:30-11:00 and didn't leave until it closed around 6:00 or so. I highly recommend it. I believe Rick talks about it in his book.
I've been reading about Italy and Rome in particular and find myself wondering how I would ever fit everything into a week in that city. Way too much to see and do, so we're trying to narrow down some of the more important things and try to squeeze a day or two into enjoying short trips out.
I've only met one person who didn't like Rome. Met him coming out of the library today. When I asked what he thought of the city, he told me he found that it was "too old." He didn't seem terribly impressed. Weird, huh?