I am no fan of Sen. McCain and I've complained that he's given far too much attention by the national press corps before and this NY Times article puts some numbers to my claim: Since January 1, 2009, McCain has appeared on at least one of the Sunday news shows 97 times and that means he's the most frequent guest. Second place is held by Goober Graham (85 times) followed closely by David Axelrod (83 times).
I copied the NYT data into Excel and looked at just the people who appeared at least 5 times (668) and summed their total appearances (4814). That's a little over half of all the appearances and within that, there are 182 who are identified one way or another as Republicans and they appeared 1,568 times. Only 28 were identified as Democrat and they appeared a total of 265 times.
Of the remaining who were not identified as either Republican or Democrat, there were 166 who appeared a total of 1026 times. I had to sort these by hand into liberal or conservative and there's room here for some disagreement so I'm taking my time and will post later.