In my past year as the Pacific Northwest specialist for JancisRobinson.com, three things have become abundantly clear. One, I will taste large amounts of mediocre wine. Two, you can avoid this. And three, it takes about a decade before a brand name becomes so well known for quality that getting the wines becomes difficult.
My recommendation for buying good wine from the US is as follows: look for well-regarded or historically lauded producers. If you find that their wines are allocated, nose around to find out...