I'm all for the class gift nowadays. The regular parent volunteers in my son's class have much better ideas for the teacher than I do and it saves me time as well. I mail the check to a mom and the teacher gets a great big gift that's personalized for her likes. Win-win!
I usually bake cookies or muffins for end of the year gifts and give gift cards with cookies and tea at Christmas, with a card. When the kids were a little younger, I had them make homemade cards too. I know a lot of schools where parents chip in for a class gift but ours doesn't do that.
I think it's far more genuine to do something personalized like you do anyway (rather than awkwardly contributing $$ for a group gift/gift card). For now, I like when my kids actually get creative themselves in an effort to show how to give meaningful gifts above writing a check.