I am assuming you are looking at Winnebago Views. I found floorplans for the '08 H and the '09 A online. A lot will depend on how you plan to use your RV, but the A is a lot more spacious. An extra 30K miles on a diesel motor is not significant I have been told. Which feels better?
Anything is possible, it just costs $, but many have replaced booth dinettes with table and chairs. What is wrong with the air bed? If it is a Select Comfort Sleep Number bed they have long warranties. I had an inflator go bad after about 4 years and they sent me a new one, no charge.
Are you sure you wouldn't rather have a full-time bed? If you plan to sleep overnight much, a sofa bed will get old really quick.
Barb (RVM18), Sena (capuchin monkey, RVM Head Mascot) & Lily (Maltese/Yorkie)
2011 Shasta Cynara 230F & 2012 Smart Car toad, 272 watt solar system
The Journey is Our Destination. Full-timing since 5/18/2011 and loving it.