Weir quay's a fine place - bit of a windy drive to get there, but a lovely spot - quite a long way up the Tamar from open water, but the whole area's great. Wouldn't mind keeping my own boat there if it wasn't for the fact that I get preferential rates working for a competitor! If space there's short, then check out Torpoint Mosquito Sailing Club - really friendly, with a great bar, less sailing time to the breakwater, and just off the end of the ferries across the river for easy access from the Devon side.
I grew up in Plymouth and will go back once I have retired (or sooner if I can get a transfer). I have considered TMSC so your notes are well received. What do you know of Saltash SC?
Saltash SC is ok, but can get noisy at weekends as it's very close to two other pubs, and there's not a lot of room to park. Tamar sailing club on the other side of the river from Saltash is an option - very much a co-op sort of club, where everyone pitches in to help with everything.