DD14 and I did the chef's counter last October. It was on a Wednesday night and we had 5:30 PS's, but we could have just walked in; there was only one other couple seated at the counter and they weren't that busy.
It was fabulous. It's so expensive, so be prepared (take a look at the menu on allears.net) but so worth it, in my opinion. They were so sweet to my teenaged daughter, told her all about her food and how it was prepared, etc. The head chef shook our hands and pointed out where everything is done in the kitchen. DD said it was like being on her "own personal Iron Chef!"
I've dined in many fine places including LA, San Francisco, Seattle, London and Madrid. Napa was really one of the nicer places I've ever been.