I'm the PTO President at my kids school. We have a Hospitality Co-od and I gave her a few ideas, but she came up with most. Here's a copy from her email as to what we'll be doing.
Monday....Coffee and Danish day. "Thanks a Latte." (catered by local coffee shop)
Tuesday...Present each teacher and staff with a vase and flower. "Thanks for helping us Bloom." This is where the letter I will send home with the students will come in handy. Asking the students to bring in a flower, real, silk, homemade or even a packet of seeds.
Wednesday...Have a dessert day in the conference room and do a set up similar to the birthday celebrations.
Thursday...place a small votive candle or sash of potpourri in the mailboxes "You are 'sent' sational."
Friday...Round out the end of the week with a lunch from Substation. a Mary Kay consultant coming in on Friday of teacher appreciation week to do hand massages and a hand silkening treatments between 10 and 2pm!!! Totally free of charge!!!!
Some other ideas...
A recipe day, "Recipe for success". Ask the parents to send in a copy of their families favorite recipe to the teacher and assistant.
A Student Choice Day..."Thanks for making our lives fun." This is where they can be creative with ideas leaning towards fun items for the classroom or basic classroom needs...pencils, glue, etc..
Cards for their teacher...this would probably be on Friday. Ask the students to purchase or hand make a Thank you card for their staff.
Don't forget PE, music, librarians, etc. teachers as well.
We also have a sign in the front of the school that lists activities, no school days, etc. and we put TA week on there, so parents can do something special on their own too.
HTH!