I went to Reim last June. It was an pretty short trip for 2 days. But we made most of it by visiting impressive champagne houses. They are Pommery and Mumm. Mumm was quite average but good to see well displayed making process. Pommery is the must-go place. It integrate Champagnes with find arts in their galleries(cellars). and the buildings.. They also have Micellin star(2stars i think) restaurant next to the house.
I would recomend you stay a bit longer than I did and do make a reservation befor you visit.
As long as it is too famouse like Krug, you are able to get invited. I hope you enjoy! by the way you have to pay admission around 15 to 20 euros.