In our household, I would really prefer a gift certificate with a "category" of what I'm supposed to get.
I have so much of everything in the sewing/quilting category, that I frequently end up just looking - even when things are on sale!
I won't buy tools for my husband - he's picky - and if he sends me out to buy a part or whatever, I have him either give me a screw or whatever and then go to the store person and ask for help - or write down the part number.
Then, if it's wrong - - - - -
You could go shopping together - see what catches her eye - - -
(Although if MY husband offered to go fabric/quilt store shopping WITH me, I might suffer a heart attack from surprise!)