Weekend break near Brussels - looking for tips

I'm looking for a hotel/spa/château/country house hotel etc. for a short weekend break, within 80 km from Brussels. Somwhere close to nature, where it would be easy to have a long walk; some good food; and general rest and relaxation. I've been to Château du Lac and Dolce La Hulpe and liked those, so something along the same lines. Would be grateful for any tips!