Best experience I've had was Cooper GMC in Stillwater, Ok. A couple of Christmases ago, our F-150 was having problems. We took it to the Ford dealer, who called us back saying it was the intake manifold, which was under an "intergalactic backorder". This is after we'd had it in 4 times in 3 years, for over $5k worth of work. I'd been on the fence about trading it in before the latest malfunction, and this pushed me over the edge. I'd even gone to Carmax a few weeks prior just to see what they'd quote on a trade in.
So now, we're out of town, and HAVE to get a new vehicle. I looked at a few dealers, in the Stillwater/OKC areas and wasn't happy with the prices for the quality, and decided to up my price range about $10k. I went to Cooper, and explained what I was looking for, and the price range. They brought out a few trucks for me, 3 of which I liked (Dodge Power Wagon, and 2 GMC AT4s).
I went and got the wife, as this was to be her vehicle, which would also be used for towing our camper, and brought her back. She fell in love with an AT4, which was a bit above what I had told the dealer our range was. I explained this to the dealer, who went to the back, before coming back with a better offer. He offered to take our trade in for the Carmax quoted price (which was before the latest issue), and took the price of the AT4 down to our price range if we were to finance through them. Yes, it was a higher APR than I could get on my own, but there was no penalty for paying it off early, and the difference in prices was worth it.
He then goes to the back again, to finalize the deal before we go back to sign the paperwork. While he's back there, my wife and I are tossing around ideas, and decide that paying another $10k down on top of the trade would make more sense, and a much easier monthly payment. I kind of felt dirty asking the sales person about taking the extra down payment when he came back, as it changed all kinds of numbers we'd already agreed to, but he took the offer back without complaining, and the dealer accepted the offer. We signed the paperwork that day.
All in all, it was a very easy process. They didn't have any addon fees or anything, and even though we changed the deal which gave them a worse deal, they accepted it without any counters or grumbling. I walked away pleasantly surprised that there was a dealer that worked like that.