Sorry I accidentally posted the drop bar conversion link first instead of the upright conversion. Useful to recall that those are all the same type of frame, but with a quill stem, it is easy to make changes to height and reach.
I’d also agree that Rivendell might be a good brand to try out. I also joke that my RockHopper is what a Jones bike wishes it could be like, though it’s perhaps more apt to call it a low budget version of a Jones bike.
Anyway, this is the sort of relaxed fit I’m riding that may be what the OP would want. I do perhaps longer and faster rides, but obviously it would be well suited for all-round recreational rides (probably with derailleur gears or maybe an IGH, rather than single speed as I ride it).
The stem clamp is about level with the saddle and the bars have two inch rise, but angle down. I’m using a long stem so there is a good range of grip from all the way forward (about like drop bar hoods at the forward bend) to a much closer position at the grips.
The Jones ends up with a similar fore-aft range but the bars are wider and angle at 45 degrees while these angle back at 70 degrees.
I should add, I’m using the long Nitto stem adapter, so the stem and bars could easily work on a modern threadless fork.
Otto