My wife and I are planning the same trip for the end of May. I'm interested in stopping one night in the Mulhouse/Colmer area and visiting the Schlumpf auto museum. Something that I've wanted to do for years It's about half way between Munich and Paris.
Our travel agent (the same one that puts together the BMW tours) has recommended the Chateau D'Isenbourg. It looks great and I suggest you check it out.
Where are you staying in Paris? Wer're still scoping out hotels there.