Not necessarily going to be a discount (If I did it would more likely be $75 for that third night).
I was thinking more along the lines of added value. I thougth about a 75 minutes massage package - again, the massg therapist has to be paid, so it is not out of my pocket but theirs) I also thought about this anniversary and celebrating THEIR anniversary package of some sort.
(I started the picnic for two on another thread to see if maybe that is something I could do...just a thought..as an added value for this 75 year anniversary.)