While there a few gamestores in Eugene, there isn't really a great one.
My favorite is probably Emerald City Comics, as they usually get stuff as its released, have a good selection of new and used gaming stuff, and all new gaming materials are 10% off cover price. The majority of the staff are friendly and knowledgeable, with one exception. There is no space to play there.
Just down the road lies Planet of Sand, which specializes in miniature combat games. They have a decent selection of new and used stuff, and charge cover price for everything. They tend not to get RPG stuff until everyone else has had it for two weeks, and the staff seems pretty un-knowledgable about RPGs. They have several tables for playing, one is even in its own room, which is cool. Unfortunately, the table are almost always taken by board and mini gamers. The few times I saw people playing D&D, there were only the young unwashed masses of munchkin types I don't typically enjoy playing with. They do have the best fantasy mini selection in town, and carry tons of reaper stuff, which is pretty cool.