The BEST way to restore them is go to some local car shows, find an old restored car that has a perfect interior, and ask the guy who did the work. Then take the car by their shop and have them restore the seats. They can make new seat covers either stock or they can dress them up a bit, and you can have some extra padding added to make them more comfortable. They aren't bad as they are but they can be made a bit softer.
I would say the best way is to pick up a set of factory replacement seat covers, but they cost through the nose and that assumes they still have any in your color.
A do it yourself cheapo solution would be to go find some SEM leather dye and respray the seats. You'll need to clean them thoroughly (SEM has directions on seat prep on their website, curiously not on the product cans) the respray the seats. You'll want very light coats, with 30 minutes between coats. Once the seats are redyed to your satisfaction, let them sit for a week before use. This is also better done in the summer, because it takes forever to fully cure when cold. I did mine and they came out OK, but I didn't use light enough coats and it was a bit colder than I wanted so some of it has come off. I plan to redo them this summer with lighter coats where the stuff came off, but when I finished they looked almost new.
