The Gibbs Room is located in the Davis Art Building (a long, colonnaded building on the south side of the main Sloane Quadrangle quad). It's close to the gym, which is on the Vine Street side of MBA. (The football stadium is on the Wilson Avenue side of campus). There is free parking alongside the gym and beside the Massey Junior School (again, on the side of Vine Street Christian Church).
And a friendly reminder: If you have not recently done so, please take a moment to renew--or begin!--your membership with the national JASNA organization. Check out JASNA's new online Member Portal to take care of business in a flash.