I too plan on attending this year. My club is hosting a booth and I can't wait to try the beer of other brewers from across the country. One thing to keep in mind is the NHC isn't really in Seattle, it is in Bellevue. So you will need to do a bit of traveling to get to places like Brouwers, Bottleworks, Malt & Vine, Uber, Naked City and other places known for their commercial beer offerings. There is a plan to do some brewery tours as well.
As for food, there are plenty of great restaurants in the Bellevue area. Some can cost you boatloads, like Daniels Broiler, but other places like Rock Bottom are tasty and affordable.
On a side note, the weekend before (fathers day) is the Washington Brewers Fest. So if you really want to make a week event of things this fest is always a fun one, and it is family friendly except on Friday night.