I would recommend a little research on the tripadvisor website
http://www.tripadvisor.com/
Just type 'Rome' into the search box to get an unbiased listing of all hotels.
I'm not sure I can wholehearted recommend any of the hotels I've used, as they are at the upper end of the price scale, however, I found that choosing a location close to the 'Spanish Steps' can be very useful, as much of the sightseeing is then within walking distance, hence not being dependent on, or paying for, public transport or taxis.