I'm big on appreciation gifts - because these are the people who spend a large quantity of time with my son, and I appreciate that! I don't know where I'd be without them.
I honestly think money is the best gift. Seriously, if you were a daycare worker, would you want a giftcard to x store (you may not even shop there) or some cash? Most daycare workers really don't make a great living and could probably use the extra cash around the holidays.
As such, I give $100 to each FT daycare teacher (4 - total $400), and I plan on giving at least 25 to the other flex teachers that occasionally fill in the room (about 5 of those, so I'm planning on around 150 - 175 for this category of teachers). I wish I could give them more but it has been a tough year for me financially with a family illness that has been a huge financial drain.
I also give them each a nice card with a picture of my daughter holding up a little heart sign that says "I love you Miss XXX" and a nice note expressing my gratitude for their great care throughout the year.
In my opinion, I would rather be over generous with the people that basically spend as much (or more) time with my daughter than myself. They certainly deserve it and I can cut back in other areas to make up for the cost. If anybody deserves a generous gift, it is the people that care for our children every day.