A solid color is nice or add an insert for a little more of a variety. Black/grey or vice versa would look nice or if you have any other accent colors that's an option as well, but can sometimes look tacky. Best thing imo is to just do something that'll still retain a somewhat stock appearence. If you're interested, check out
Katzkin Leather to have some upholstery made up. I've used them before and they are a VERY nice and HIGH quality leather replacement. If you're up for doing it yourself this is the ticket as going to a shop is usually extremely expensive especially for custom upholstery. They send with all the hardware you need. It is not hard to take your existing leather off and the new stuff goes on easy too. Takes maybe a few hours out of your weekend to do. Just my .02