My parents just drive me crazy at the holidays! They, as many have noted, have everything! I...attempting to be a thoughtful gift giver....listen when we are having conversations throughout the year to things that they say they want to try or have and them give it to them....only for it not to be used!!!! Oh well, at least they have it!!! 2 years ago my sibs and I purchased a GPS system for my dad. He was thrilled....it hasn't been used. Ditto for the IPOD when they first came out and a couple of other electronic things. He LOVES his laptops so it is not that he doesn't appreciate technology. I mentioned a KINDLE to my mom...neither have the slightest clue as to what it is...gotta love them!
For a couple of years a did an excellent wine company - Fruit Forward - for my dad. You can do a wine of the month every month, every other, every 3 or 4 or 6. They usually send one red and one white but if one prefers only one of the 2, that can be done as well. My dad really enjoys different wines and he loved this. It is expensive to ship so I was on the every 4 months plan which worked well for him.
My mom, I just try to go with what is functional. I like what a pp mentioned about buying a years supply of something. I bet if I purchased a years supply of DUCT TAPE my mom would be in 7th Heaven!!!!

Boy! She could tape the entire house up! Broken gutters? no problem! Car door falling off...who need another one...just duct tape it!!! Cut on your finger? eh...put a little duct tape on !! She's like Tulla's father with the windex in My Big Fat Greek Wedding!!!
Oh well! At any rate, my mom has been doing a compost for years using a margarine container in the house and she loves my "official" compost pail. I am getting one for her this year.
We also have great luck with tickets to musical events as my dad is a retired musician. We also started out paying my parent's membership at the community rec building....mom never used it, dad uses it to this day (10 or so years later) so doing that and just renewing the membership is great!