I agree that the Fal and the Helford estuary would be a great venue for a cruising rally. I have sailed in this area on several occasions during the last few years and always discover new creeks to explore. The passage from Falmouth to the Helford Estuary makes an interesting day sail with a lunchtime break at the Ferry Inn. We have stayed at Cosawes campsite and kept our boat at Mylor Marina which is only a few miles away. The marina has good launching facilities, changing rooms, chandlery, restaurants etc.
May I also suggest that you consider a weekend rally at the Mountbatten Sailing Centre, Plymouth. It is very similar to the Calshot Activity Centre, Southampton and provides inexpensive b&b accommodation as well as good storage and launching facilities, changing rooms and bar! Plymouth Sound also offers an extensive and sheltered cruising area with the added option of a short sea passage to Newton Ferrers/Noss Mayo in the River Yealm. http://www.mount-batten-centre.com
I have thoroughly enjoyed attending the excellent rallies organised by John Norman and Jenny Jeffries at Calshot. Their rallies have given us the experience and confidence to be a little more adventurous and I think that any of the venues mentioned above would be suitable for the less experienced Wayfarer sailors. It would make a change to see the West Country hosting some of next years cruising events.