Ballard is a great place to go for beer.
If you are interested in Nanos specifically, I would recommend Epic Ales & Gastropod in Sodo. They are the smallest brewery I know of that has made it work in the city. Reuben's (Ballard) is pretty small, and probably the best beer in Seattle. Most of the other Ballard breweries are very well capitalized, and opened with 7-20 barrel breweries. Outside of Seattle is where most of the true nanos are. Justice Brewing in Everett is great doing belgian and strange beers (Disclaimer: I am friends of the owner), Foggy Noggin in Bothell is run out of a guy's house, and has a tasting room open on Saturdays, making solid English style ales. Other Small breweries are Geaux (Bellevue), Bushnell (Redmond), Big Al (White Center), and Dirty Bucket (Woodinville). Another person you might want to talk to is Derek at 192 brewing in Kenmore. He runs a brewery out of his property, with a taproom/beer bar in town. I might be able to meet you for a beer on Friday or Saturday night if you end up on the north end.