Maybe try this one if it is close enough for you? They are well regarded, fairly casual, are in a great location (walking, biking, etc.), and have good sports facilities (spa/pool, etc.).

http://www.holtweijde.nl/

I also suggest a day or two near the Hoge Veluwe national park - free bikes and the Kroller Moller museum - one of the best in the world in my opinion. Not sure about hotel options though - few near there could be considered true luxury.