We want something that is 1) inexpensive, 2) light weight, 3) easy to use, and 4) effective (not necessarily in that order.)

A ring buoy is an obvious choice. But it would have the drawback of being big and bulky, not to mention dorky. I just don't see CJ walking along the shore, following me, with a ring buoy over his shoulder. He isn't a lifeguard, just a husband who doesn't want to feel helpless if his partner is needing assistance.
So then

The plan now is to do a little more research and make a purchasing decision. I'll keep things updated when it comes in.