oooo...a small round table for the PW Plateau, that sounds like a great idea!
I have 2011 and I have the rectangle table like you describe, I've only used it once (I have only had the coach for a month so..) but I can't see myself using it much - especially since you have to climb over it in order to sit on the couch when the table is out and it's not very stable. I find myself using the flip out counter top as a table, even though it's a bit high. A round table might be better - less table surface space but easier to move around.
I think I'm going to get a small lap desk to use a table in the event that I'm "stuck inside", otherwise I'll prob just use the picnic table in the campground!
I have no thoughts on how to obtain a round table, but when you find out post here, I might want one!
I like Davyyd's DIY idea as well...