Trevista Vineyards is a tiny Valle de Guadalupe producer, useful for travellers who want a more personal stop than the large, polished wineries. Production is small, visits may need to be arranged ahead, and the appeal is in seeing how a boutique winery works at close range.
Do not treat it as a guaranteed drop-in tasting room. Call first, and fold it into a wider day of winery visits in the valley.