Reins is fantastic and Pommery is a great choice to start. I only got to spend one day touring and tasting and we were still able to see a lot. The Cathedral/Palace of Tau/Basilica/Museum are must sees.
I would suggest picking only a few "big name" places to tour and spend more time finding smaller/family wineries to taste at. The tours will be pretty much the same at all properties. I really enjoyed Lanson and Tattinger. This list is a good place to start:
https://www.champagne-booking.com/en/champagne-houses/?fromPoint=49.26528,4.02861,25&sort_by=asc%3Adistance&title=Champagne%20Houses%20in%20Reims%20and%20nearbyAlso, it's fun to walk in the vineyards and see which houses have grapes in certain rows. A few rows up or down and the soil/sun/fog/etc. affect the vines differently.
If you want to balance champagne and history, Verdun is about an hour train ride away.