I've gone with the Caddis Navigator II. It's a big tube with a weight capacity of 350 pounds. It looks big enough to float a Volkswagen. I think it will not only be comfortable but it will float me quite adequately. I'm not crazy about the valve systems, but once I get used to setting it up I think I'll be happy with it. Here's a link, scroll down;
http://www.caddissports.com/navigator.htm
Now I need to take it fishing.....