I'm letting my 4 year old pick all presents for adult family this year. He's been doing it for friend's birthday parties for a year or so, and it's so much easier.
Admittedly, he's pretty sure that all adults want either coffee or Hotwheels, so I'll do some gentle steering, but I tend to think that presents are for kids at Christmas, and adults get something token, and by letting him pick it gets him involved.
DP might get something for his mum, but he got something big last year, so he might just stick with my plan.