I think instead of just a "blue" theme, a "recipient's favorite color" theme would appeal to more people.
I like holiday themes, e.g., trick or treat, things you're thankful for (useful household items), or lucky charms.
What about tea time or time for a coffee break -- tea bags or coffee and little snacks and mugs or teacups?
Back to school could be a fun theme--cute office supplies or stationery
Bag it up: any kind of small bag, like a lunch bag or purse or makeup bag or reusable shopping bag
Minis: anything miniature, like small candy or small packets of treats, or sample size lip glosses and lotions, or anything someone likes that is small or at least smaller than normal size; cute little figurines or erasers or maybe small packs of accessories or pins.
Sparkle time: things that are shiny or sparkly -- gold, silver, glitter, eetc