I went the whole nine yards: Baldwin seat, upon which I have the Airhawk 2, and over that i have the Alaskan sheepskin. Overkill? Maybe, but I have lots of options, depending on the length of the ride and the temperature. For extended highway riding, I put a little extra air in the 'hawk, since I don't have to shift my weight around. For a limited set of twisties, I take off the 'hawk completely.
So far, so good.