I have a reservation at San Francesco Hotel in Trastevere but thinking that since it is my first visit to Rome I should stay closer to the historic center.
I would love to stay in Campo d' Fiore, Navona or the Pantheon neighborhood. Do not want to stay near Termini or Spanish Steps.
Any thoughts

We've stayed multiple times at the Hotel Fontanella Borghese which is about halfway between the Spanish Steps and both the Pantheon and Piazza Navona. I think it's in the same general rate range as the San Francesco.

http://www.fontanellaborghese.com/en/

Hotel Abruzzi (http://www.hotelabruzzi.it/) is opposite the Pantheon. I've not stayed at this property but have heard it is very nice.

I am not a fan of staying in the Trastevere, as I feel it is a bit far to walk from there to other favorite (for me) historic sites. Great for a visit, though! We always stay at the Parlamento... basic, but family owned and located right in the center nearish Spanish Steps. See if you can get a room that connects off of the simple rooftop area... nice to sit out there with some wine.

Hotel Modigliani.

We stayed at Hotel Campo de Fiore for 5 nights n September and can highly recommend. The location is right around the corner from the market with tons of restaurants and shops nearby (the various Roscioli venues are terrific and the best tiramisu ever is around the corner at Zum).
The staff is helpful, the hotel is beautifully decorated and spotlessly clean. There is a cool rooftop terrace to sit back and enjoy the evening sunset and the staff will bring you a drink upon request.
It is a very short walk to Piazza Navona and only slightly longer to the Pantheon. Beyond there, it is still an easy stroll to Trevi and only a bit more to the Spanish Steps. In the other direction, you can easily walk to the Ponte Sisto and into Trastevere.

Thank you
Deciding bet Hotel Navona, Hotel Campo de Fiore and Hotel Del Barbieri. Hoping to be in that triangle-campo/navona/pantheon

That 'triangle' is too tourist-crowded for me. I find Rome very walkable for what otherwise seems like a big city, and I'd rather be 5-10 minutes outside of that triangle. To each, his/her own...