Seattle's a fun city, and more varied than the media makes it out to be. There are certainly plenty of fleece-wearing, keyboard-tapping tech nerds, and also a goodly number of crunchy liberals of all varieties, but Seattle was a lumber/shipping/fishing port for a really long time before the coffee and tech crowd moved in and there are those folks (or their children) around too, which the local politicians manage to forget on a regular basis for some reason. And with Bremerton and Joint Base Lewis-McChord nearby, military and ex-military folks aren't unusual. (And I will say, although the coffee culture is very eyeroll-worthy, it also serves an actual purpose in the cold, damp Seattle weather. Many a day waiting for the bus in January was better with a hot beverage.)The U District is relatively convenient and definitely central to the public transit system, with the light rail due to arrive there very soon.
Per grocery shopping, when I lived there I was carfree and Safeway was the cheapest thing I had access to, but my sister (who does have a car) seems to find Fred Meyer and Costco to be her favorites. Lots of Trader Joe's available, but if you haven't had access to one before, check out a Grocery Outlet. It is a WEIRD assortment of stuff, but fun to poke around in and what you do buy will be much cheaper than average. Another place that has good prices on what it is (but keep in mind we're talking about imports, so price is relative) is Pacific Food Imports south of downtown. Amazing cheese and olives but they make you buy good-size quantities so I always went in with someone when I shopped there.
For veggies, The neighborhood Farmers Markets (the U District has a great one) and Pike Place Market are a lot of fun to walk around but I always found them to be pretty expensive. If you are the kind of person who wants organic produce, I found a weekly CSA box to be a much better deal, or if you want to buy as you go and don't care about organic, Rising Sun Produce Market had great prices but is definitely not fancy and usually not organic. If you have a lady (or gentleman) friend, or Mom, visiting who likes flowers, those are $5 for a good-size bunch or $10 for an enormous bunch at Pike Place Market, cheaper than the farmers' markets. (Buy them right before you leave, though, buying first and having to carry them around is something newbies fall for all the time) The food culture is pretty twee, but the thing is, the food is SO good. I miss the amazing bakeries, and cider, and summer stone fruits (cherries! peaches! plums!--spend the money at the farmer's market for those), etc etc.