I had the same issue. After a decade plus of surfing in FL and Hawaii my interior looked like a grenade went off in it. People would actually wipe my seats with their hands before sitting on them.....after I had cleaned them. All the cushions were collapsed and offered no support.
After a little thought I decided to invest in the Katskins line. Probably a good choice. A little pricey, I had the shop do a bunch of additional work on top of the interior so that added to the tab.
But the shop completely rebuilt the original seats. New cushions and foam and all the support is back like new. And you can do just about any combo one can conceive. I was blown away when picked it up.....did new carpet and overhead liner. Had them take the nets out the back of the front seats and did tight pockets. Got that new car smell back!
They make pre fab cutouts for tahoes so that brings the price down a bunch.
Cheers!