I definitely don't want some fanny-pack kind of thing. I'm a pretty good swimmer and if I have my wits about me well enough to use one I can probably just swim. I'm more concerned with something that will help me survive in less than ideal circumstances.
Being able to nurse in a vest is not a high priority at this point; it's only a theoretical concern anyway. I'm a lot more interested in just something that would be comfortable.
I'd rather avoid an inflatable if I can, but it's definitely an option. Thanks for the suggestions!