Is there really no topic on this? I just finished "buying" (leasing) my 2018 SL, but we obviously need a topic in which to compare deals, dealerships, and salespeople. I'm going to recommend, for the Upstate NY Capital District and surrounding areas, Lia Nissan in Colonie/Schenectady.
I'm especially going to recommend David Seacord, who didn't just surprise me with his diligence, helpfulness and general great manners - he amazed me. He even went to far as to get me a further discount after I had agreed to lease my car. He was the only salesperson willing to handle negotiations over email, and he did it very well: he is as easy to correspond with as he is to talk with. I met him in person for the first time this evening, when I picked the car up. The Sales Manager there, whose name I have forgotten but will add later, was also great: no pressure to buy add-ons, and once he was free I was in and out of his office in about 15 minutes.
On the flip side, I'd like to suggest that Leaf shoppers avoid Destination Nissan in Albany NY. I leased my 2013 SV there, and got a fantastic deal, but times change, and entire dealership staffing along with it - several times in this case. When I approached them to order a 2018 Leaf, they arranged a test drive readily enough, but then the Sales Manager informed me, rather snippily, that they didn't "do" factory orders, and that if I wanted a Leaf I'd have to choose from the (three, IIRC) cars they had in stock. The salesperson I dealt with for the test drive was fine, but dealership policy trumps individual salespeople...