FELT TREE....My playroom and nap room are attached and I keep the nap room door shut. I hung my tree on there last year with tape. It does come off from time to time but it's not a huge issue. I allow the kids to rearrange the ornaments and they will play this quite a bit. I have posters on my walls too and they know they aren't allowed to touch those unless we are doing circle time and they come up to them and point to what is their favourite.

If a door isn't an option and you don't want to use tape, you could use painters tape too. I use that a lot.