Some common truths:
1) The parking lot will be full of either hybrids or Subarus. Most will sport a bumpersticker of Hope/Unite/Coexist yet the customers driving these cars really don't embrace these philosophies (as they are some of the most snootiest (is that a word?) in town)
2) Most of the customer's are wearing some sort of patagonia jacket/keen footwear and they all believe in layering.
3) You will leave the store wondering, "How can this little amount of stuff be sooo expensive?"
With that said, I believe Whole Foods has one of the best fish counters in town. The mongers are well informed and happy to help. As well, there deli case and prepared foods won't leave you disappointed. I especially love their Israeli couscous with cranberries...seriously addicting. Cheese selections are pretty on point with a good selection of international cheeses.
As long as you come into the store knowing what you want to get (vs. general grocery shopping), you will fare well. Just remember to leave that Bush/Quayle '88 shirt at home if you don't want to face the stare of death of everyone and their mother while shopping.....