Andrew,
I think it makes more sense to talk about tons than about feet or metres. Personally, I prefer boats which are moderately long for their displacement. More length (within reason) both raises the cruising speed and makes better room for the JR and its sheets.
The problem with raising the displacement, is that all the bits in the rig, plus the engine size and fuel consumption goes up. Rudders and self-steering gears must also be of bigger size (expensive), etc, etc. I have sailed a 23ton JR schooner. It is all right in a sunny breeze along the coast, but that thing is still a ship, rather than a yacht. Its engine is way too big for manual starting, so all sorts of backups (battery banks) are needed. Same with the rig. Winches and ropes are in a different league. Just scrubbing and painting the thing is a project compared to on a 4-8ton vessel.
I would rather look for the smallest boat for the task, than the biggest. David’s displacement numbers makes sense, that is, for long term cruising. For weekend or holiday, coastal cruising, I would say lighter is better.
It also depends on one’s approach to boating and sailing. Do you want a floating home which can be sailed, or do you want a enjoyable sailboat, which can be lived on over a shorter or longer period of time?
Arne