I also have the closet full of stuff. I love the idea that DD has a great christmas in her mind and I am only out $100. About buying stuff for the Sil in Law or Sister: I throught it all in a theme basket. So with your bath robe I would throw in some Bath and body shop stuff I have already bought at the annual sale for 75% off. And if I have some thing that is odd or left over, darn I might just have to keep it for myself.
This year one of the Sis in Laws is getting a drinking themed basket. I got a awesome Crate and Barrel wine opener for $5, some drink glass sugar rimmer type things I got on clearence this spring, I have some cute crate and barrel stir sticks I found last year, So a favorite bottle of wine or booze will complete the gift once Christmas comes. (We have a $30 limit but I figure if I got it on sale I wont be stingy so its actually got a gift value of $55-60 but I only spent $30)
My sister and I are really warped! We give each other the big box o' stuff each year. The only rule is you dont pay full price for something! So we pick up stuff the other would like all year long on sale and even garage sales. Her last box had kitchen towels, candles, partylite candle holder (consultant selling out new stuff!!!!!) picture frame, some books, etc. Its become an odd family tradition since we were teenagers with very limited funds.