In the last 3 months I have replaced the dash and front seat covers and foam on my 2008 Yukon Denali.
I did the dash my self. It wasn't anything overly complicated but it did take me a full day. I followed one guy on Youtube who was very rough on the replacement (I wouldn't want him doing my dash!) but it gave me the info I needed. I called around and found a local Chevy dealer who gave me the repair shop price, I think it was $299. Ordering it online is cost prohibitive because of the shipping. I didn't get the front panel by the windshield at the time but now I just noticed a hairline crack on mine. I'm not sure of the price but it is a lot cheaper and probably just a 30-minute job to replace. I'll do mine after the holidays.
Also, know that the replacement dash is now a stronger design than the original with extra bracing in the crack prone areas. I still went the extra mile and epoxied paint sticks in areas that I thought would help. I just couldn't bring myself to do the stick on dash caps.
I ordered the replacement seat covers from the Seat Shop. Mine are the cashmere color. I have to admit, the quality is very good and the seats are identical. I replaced the foam on the driver's side, the passenger didn't need it. According to the Seat Shop, it is rare to replace the passenger side foam. Their Youtube videos are helpful but not great. My seat frame and hardware were a bit different from what they said it would be. You do need a sturdy and large work surface to do the seats. Just realize it will take a while and you may have a few scrapes from the metal frame as you try to work the leather. But it is not hard, the clips that GM uses are great, no hog rings to deal with.
Wait for a sale, I think I paid around $700 for the leather and foam. I am going to replace the center console armrest soon. That looks more like real upholstery stuff with a staple gun and massaging the leather.
My carpet wasn't too bad so I let it go though I was considering it. If you find a good OEM carpet supplier, let me know please.
I was going to replace the seatbelt as well, but it is pretty pricey. However, I didn't want to skimp on something as important as that. So I am holding off on that for now.
I do baby my Denali that I have had since it was almost new. With the seat change and the dash, it looks great.