I would add Northstar to the mix for Washington merlot. They specialize in great Merlot, at an excellent price point.
To echo other posts about right bank Bordeaux, usually blends with Merlot the predominant grape. With that in mind, check out Blackbird Vineyards. The Arise and Illustration bottlings are Merlot dominant blends. If you’re not in the Napa area, the Arise will probably be your best bet to find somewhere else. Huge fan of these Aaron Pott wines, along with the other Cab Franc heavy wines out of Blackbird.
Agree on the Washington State Merlots. Also, another “big boy” is Paradigm Merlot made by Heidi Peterson Barrett, who as you all know, once was the winemaker for Screaming Eagle.
As with others, I’d recco Pahlmeyer, Beringer Bancroft, Mayacamas, Northstar, and older Duckhorn.
We had a 94 Pahlmeyer blinded on us a month back and it was really a pleasant surprise.
The most impressive US Merlots I`ve had recently came from:
2005 Berringer Bancrofrt
2007 Hourglass Blueline
2001 Duckhorn Napa
1996 Ridge West Vineyard.
All were true treasures and in a blind format, I expect they would be a fav of most who sample them without knowing the country, region, producer and source.