As a teacher, I loved Target gift cards because even if there wasn't something fun at target I wanted to buy, I could use it on household items and then use the money toward whatever I wanted. I have gift cards for manicures and restaurants laying around from students I had over 5 years ago, but Target or visa gift cards, I used and enjoyed. Even more than that, I really have to second the card. The cards and letters written from the heart meant more to me than anything else.
For my daughter's teachers, I will usually have her make something for them... a bracelet, etc. and then give a target card and a have her make them a card and I write a thank you. I know how much heart they put into their work, so it makes me happy to do all I can to thank them.