Charles is your man for this stretch of coast.
For what it's worth, we spent a night at Treguier last June on a rag 'n stick job, so our requirements were different to what yours will be. Pretty quiet, not many restaurants open at 21.30 and then we had to go foraging up the hill into the town but visitors berths available on finger pontoons. There's no actual harbour there and no idea of launch sites, but would assume there would be something suitable in the vicinity. On balance, I would say that Treguier is a good place from a security point of view to base your boat because it is so quiet.
We liked Paimpol very much. Atmospheric, good places to eat & drink but much bigger & busier than Treguier and the first week in June when we were there, they had a bloody fair on the harbour wall. Under those circumstances, I wouldn't feel comfortable basing my boat there for a week and probably wouldn't choose to anyway because of the locking in and out, but apart from that, excellent.
Please write it up after the event to let us know how you get on.