hey guys I will be in rome for 4 days and looking for nice hotel anywhere from 3 to 4 stars would like it to be near the colosseum trevi fountain and all the other tourist sites. Will be traveling with my gf and no kids :)
First, the colosseum and trevi fountain are some distance apart. You need to check a map for Rome. In all of our visits to Rome we always stay in the Termini area primarily for the convenience of the transit system but also less touristy than somewhere like Trevi fountain. Also we like the restaurants in the area. Termini area is a little on the edge of the main tourist attractions but still very walkable. Two choices in that area are Hotels Sonya and Aberdeen. This is all personal preference and you will soon hear from those that do not like the Termini area.
Try scanning an old RS Helpline friend, the Ron in Rome website. He may have moved and isn't referenced as much as he used to be, but it's still a practical and informative website to peruse before visiting Rome. http://www.roninrome.com/hotels-resorts
I use the airbnb web site for wonderful, inexpensive accommodations all over Italy.
The star system in Italy is different. It has to do with certain amenities offered that you might not care about (e.g. 24 hour desk, elevator, parking). There are many 2 star places that are nicer than 3 or 4 star places.
As for location, look at a map. The Pantheon is smack in the middle of the historic center and the major sights. Get the RS Rome or Italy book for recommendations on where to stay that match with your interests and your budget. Consider the smaller B&Bs or boutique hotels.
Good luck.
Unfortunately in Rome the Metro is not much help because there are only 2 lines, and it really doesn't take you close to the major sites except for the Colosseum. Just realize that no matter where you stay you're going to be walking and/or taxiing several times. Of all the times we've been to Rome we really enjoyed staying at the 4* Hotel Napoleon with the Vittorio Emanuele metro stop about 15 steps from the front door. With a metro entrance that close you can at least hop on easily and get off at a stop in the general vicinity of where you're going. I've also stayed Repubblica Metro at Hotel Gea which is also a good basic hotel.
The previous poster is correct in that the Pantheon and Piazza Navona are dead center of the historical district, but no metro stop nearby.
Albergo Abruzzi is right on the same piazza as the Pantheon, and I found it to be very centrally located. It is a nice, comfortable, clean place.
Rudy, my wife stayed recently at the Hotel Modigliani which is a couple of blocks from the Trevi fountain. On her visit 6 months ago, the Trevi fountain was empty as so type of construction or repair was underway. The hotel is also close to the Spanish Steps. It is not cheap but it is a nicely rated hotel and my wife said it was a very nice hotel. It is also not located near the main train station and you need a taxi to get there. But, the Trevi fountain is not near the main train station either.
The Albergo del Senato is a hotel that may appeal to you--near the Pantheon in a perfect location. We have not stayed there (top end of our budget) but it gets great reviews. We will be in Rome in June and Hotel Due Torri is where we are booked--a short walk from Navonna in a quiet location.