Sonoma Dinner: Cafe la Haye, Harvest Moon Cafe, or Della Santina?
I'd vote for Harvest Moon Cafe, although the ambiance may or may not meet your definition of 'nice'. Great food, definitely. They do have a patio that would definitely be nice in good weather. Here is my fairly recent report:
I like Della Santina well enough, but don't find it compelling; I'd call it good but not great and the atmosphere is pleasant but not memorable. Haven't yet made it to Cafe la Haye, but I believe they have had some recent chef or management changes.