Serious Eats - seriouseats.com

They're not off the beaten path, but every time I visit Seattle I try to hit one of Tom Douglas' restaurants (www.tomdouglas.com). I've eaten at every one and won't hesitate to recommend any of them, but I'm particularly fond of Serious Pie and Etta's.

I think Cafe Campagne is overrated and overpriced.
I love the Stumbling Goat Bistro in Phinney Ridge, quiet and neighborhood-y, with a cozy elegance and fabulous, sustainably-raised food. In the same vein, but a little fancier, Tilth in Wallingford takes sustainable food in different directions, like her mushroom brulee. I know a number of people who work at Purple Cafe, and say the food is fantastic. The new, sneaky foodie dive is Lunchbox Laboratory in Ballard, where you can get burgers made of prime rib, lamb, a duck/pork blend called dork, and several other meats, with a wide range of fantastic toppings available, most of them made in-house; add on fries, sweet potato fries, tater tots or the mac&cheese of the day, all with different salt to choose from, and an amazing shake -- well worth it!
And if I'm going to recommend restaurants, I'd feel silly not recommending the one I work at: Coastal Kitchen in Capitol Hill is a fun fish house. Currently, we're running a Veracruz-inspired menu. Don't miss the snapper.

Tom Douglas? Yawn.

Try Sitka and Spruce. They're doing wonderful things with local, seasonal, sustainable products, and their food is genuinely innovative and delicious.

Stay away from Serious Pie. Unless you want to drop $40-50 on couple small pizzas and drinks after waiting in line for a table you may or may not be sharing with others. And speaking of waiting in lines, you have to hit up Paseo in Fremont. The best Cuban sandwiches ever...but not what you'd call a "dining experience". I second Sitka and Spruce and Quinn's.

I would go to Shultzy's Brats and Beers in the University District. They have big portions of all housemade recipes at really reasonable prices. Check out their website. They have a full bar, wonderful beers, it is clean, the staff is friendly and Rori, one of the cooks, makes a wonderful wicked pulled pork sandwich. If you like Northern Indian/Pakistanian food go to Shalimars, also in the University District, They have this dish called Jaipuri you can get it either w/veggie, chicken, lamb, beef or fish and the sauce is unbelievable. Their sister restaurant down the street Malabar, a South Indian restaurant is also great. I love the Tikka Marsala w/chicken but again you have all different types to your taste, veggie, poultry, meat or fish to go with it. Both places have a great prices and you won't leave hungry. Check out Kennyw.com, he has this really interesting food critic site. Aqua Verde is great but more then likely you will have to wait along time to get seated. If you want to splurge one time I recommend Palisades, Canlis or Ray's Boathouse, they all have fantastic views, great food and are Seattle icon's, very classy.

Cafe Lago in Montlake for awesome lasagna and gnocchi and a great slow-roasted tomato appetizer.

I recommend La Carta de Oaxaca in Ballard. Homemade Mexican. Like what you get at someone's house. A la carte style. Not smothered in melted cheese and stuck under the broiler Mexican food. I'm Mexican and my Mexican grandmoher who hates most Mexican restaurants ate everything in sight.

Whenever family is in town we always go to Dahlia Lounge and have never been disappointed. Unpretentious, good quality, consistent delicious food. Can't go wrong.
Also in Ballard is Cafe Besalu. Pastry heaven!

One of my favorite spots for Italian food when I went I lived in Seattle was Marcellos in the Roosevelt neighborhood. http://www.marcelloseattle.com/
It's like stepping into Italy. It's not quintessentially Seattle, but it's off the beaten path for sure, and fantastic.
I'll second the recommendation to go to Shultzy's in the U District. They have great cole slaw and sausages and the best shoestring fries. Yum.
Another U District great food spot is Agua Verde (http://www.aguaverde.com/) though it's best on a sunny day so you can sit on the deck.
One more suggestion, Crow in Lower Queen Anne near McCaw Hall. Small but delicious menu.

There's an amazing restaurant in Fremont called Art of the Table; it doesn't seem to be very well-known, but I don't think you'd be disappointed by it. The place is quite small — they might be able to seat 22-24 people — but that gives it a homey and intimate feel, and the chef, Dustin Ronspies, is very involved in the process. (He even poured me a beer!) My friend and I went there for "Happy Mondays," their happy hour from 5-10 p.m. every Monday (obviously), and enjoyed a number of small plates of delectable food — everything from chilled green onion soup to tomato and goat cheese tarts to duck rillettes, each between $8-10. The menu changes every week, but it all seems to be phenomenal.

I also third the recommendations for Quinn's; it combines reasonably affordable prices, a great selection of beers, and some great food. I had the braised oxtail (with rounds of brioche toast and aerated Fontina), my friend had the Wagyu cheeseburger, and we shared a mizuna salad with Stilton cheesecake. It's not for those on a tight budget, but you're getting a spectacular meal for the price.

I'm moving up to Seattle in a few months, and I can't wait to have these places (among others) at my disposal all the time. I hope you enjoy your trip, friend! :)

Here are my very favorites:

Tilth - tiny Maria Hines puts out big, beautiful locally grown food and local wines.

Union - Ethan Stowell was nominated for a JBA this year and his food is genius.

Herbfarm - Jerry Traunfeld's beautiful place and beautiful food.

Sambar has the best cocktails, and Sun Liquor is one of my favorite places to hang out with friends and drink.

And don't forget Top Pot doughnuts - yummy!

honestly guys... not too expensive, igault?? herbfarm...is super expensive,
cheaper would be the newly opened Poppy by same owner