Personally, living on the Severn Beach line, which just trundles aimlessly around suburban Bristol and has all its stations served by city buses, I'd love it to be converted to a tramline.
One train per hour (or thereabouts; the timetable is strange) is inconvenient for commuting from the suburbs into the Temple Meads area (which is what I, and the majority of my fellow passengers, use it for), and it doesn't go near Broadmead, the centre, or anywhere where it would be great competition for the buses.
If I were the in charge of it, I'd build a tram network around the city centre: one line starting at Temple Meads and going through the centre from Queen Square to Cabot Circus, another (potentially branching off the former) going up Park Street into Clifton and following the old heavy rail line back around to Temple Meads.
Then you'd get a route which is bafflingly uncovered by the buses (it's impossible to get to Easton, a significant suburb, from TM without getting off one bus, walking through the centre and getting another one), connects suburban commuters to the centre and TM with a much greater frequency, and I wouldn't have to walk up Park Street (a steep hill) every day from Rupert Street because nobody thought that maybe people who live east of Redland may need to get to Clifton at a greater frequency than ~1tph.
As a bonus, you'd get political credit for undoing cuts: if I recall correctly, that's basically where the old trams went before they killed them in favour of the buses.