I'm getting ready to start looking for an apartment in Rome. I'm leaning toward the central area for its walkability (Pza Navona and the wider surrounding area), but also considering Trastevere. If I decide to go with Trastevere, where is the part I want to be in?

My advice would be, if you are not going central, is to ensure you are on a bus/tram/metro/train route as close as possible. I've stayed in Vaticano (outside the Vatican) but in the Roman area of that name and around San Pietro. Both times pretty close to stops. Both had their own restaurants/shops etc in case I wanted somewhere close by but easy access to other areas using the 24 hour tickets.

Good luck with your search

The area closest to the Ponte Sisto seems to be very popular for dining and gathering.

I don't recall specific streets but you do want to be careful about staying right in an area that may be loud/boisterous at night. Be sure to read reviews for any mention of nightime noise.

We rented a VRBO apartment in Trastevere that offered a fantastic location.We were on the quiet side of Trastevere in a flat near Pizza Ricca on Via Genevesi. It was an enchanting, quiet area right at the door of a vibrant neighborhood of locals and tourists. We were within walking distance of many of the important sites yet were almost alone walking in the streets right around our building.

WRH Trastevere where we stay is across the main street that runs through Trastevere area, and it suited us, but it is not right on the Piazza of Santa Maria in Trastevere, a lovely and central area especially for early evening passagiata, lovely cafes, and the like. Consider searching for lodging in this area, but do consider if it is lively, it may also be noisy in the evening, so you'd want to check reviews/.

Hi A&L,
We've always found the NW corner to be the most conducive to charm. Its somewhat more quiet, and removed from the hubbub of the more westerly part. Our fave lodging there has been the 'Guest House dei Arco dei Tolomei', located in an atmospheric square. Just through the actual arch itself, one finds a local high school/secondary school. Our norm has been to dine elsewhere deeper into Trastevere, then return to that NW corner for its less hectic quality.
*Maybe also check out the Monti neighbourhood for lodging? It has plenty to offer, with a more genuine residential feel amidst the attractions.
I am done. The end.

Like Zebec we enjoyed staying in Monti very much, but if this is a first trip to Rome, I think that I would prefer to be somewhere a little more central. For us the area around the Via Coronari was perfect - off the main tourist drag but very close to most of what you'd want to see.