Hudson Valley Wineries
Millbrook is the best in the area...not sure they currently have a Riesling though...in some years, their pinot noir is really good...very good cab franc annually and a tocai friulano. They own Williams Selyem...one of the first Napa mail order boutique wineries...their wines are usually mailing list or select retail available, but you can buy them at Millbrook. Oak Summit in Millbrook sounds interesting. Whitecliff is carried at Astor Wines on occasion so I imagine they are pretty good at least. Stoutridge is a wine geek's curiosity stop...biodynamic, minimal intervention winemaking...you can only buy wines at the winery...they wont ship because they aren't stabilized with any additives. They pumped a lot of money into the place...interesting story.
https://whatisleftbehind.wordpress.com/2014/01/19/the-hudson-valley-winery/
Just thought I'd link to an article about the winery in Highland NY that my grandfather's family worked for years, following their move to the US from Italy. One of my great aunts still lives on the property. I still remember how cool the insides of the stone buildings were in the summer.
It's closed to the public now, but you can still go and look around if you don't mind a little trespassing. 
We're taking a last-minute trip to the Hudson Valley (between Cold Spring and Hillsdale) and I'm wondering if anyone has any must-visit winery suggestions. The type of wine doesn't really matter, though I'm partial to Rieslings. Anything that's a particularly lovely setting would be great!