Well there sure are varied opinions on mattresses. We have a Select Comfort (Camping World Edition 72X80) in our Bighorn. I believe it is the same as the Select Comfort 4000 series. WE LIKE IT! It is also very light weight. Since we now have a house as well and couldn't afford a 2nd air bed, we found a king size tempurpedic (memory foam) and love it as well. Found on Craigslist for $75. A steal!!! It is very very heavy though.
For our comfort needs, I think we have the best of both worlds. Everyones body has different comfort needs. Find one you like and go for it.