I always put at least one lime green Mickey head with my DIS name on it, on the window, just to make it easy to find my room.

However, I also have Disney clings for Christmas, Halloween, and Spring (Tink and friends with flowers), that I use if I'm down there during that time. I also have some cute purple mini lights that I've used if I'm down there in Oct and some clear mini lights for Christmas. I also have some orange and black Home Depot Mickey heads that I've strung on 1/4" black satin ribbon that I use as a swag with the Halloween clings, then have another swag made with all different color Mickey Heads strung on a light pink skinny ribbon that I use with the Tink Flower Festival clings.
When we were there Feb 4th-11th with our 3 y/o grandson, I had had someone over on the creative designs board make me character license plates with my, my husband's and my grandson's names on them, then laminated them and used them on the window at POFQ. My GS loved it. Every time we came back to our room, he'd point to his name and say "that's our room. I see my name".
I always carry a small (like 3oz) spray bottle of windex though and clean the windows before we leave. In fact, the windows are always cleaner when we leave than when we arrived.

Also I would never use tape on a painted service. There'd be a good chance the paint might come off with the tape.
One mistake I made when I was down there one Dec: I bought one of those large Christmas door panels that plays music if you walk by it or get within a certain distance. It covered the entire door. I did use tape that one trip on the top, bottom, and sides of the door to put it up, then hung the connected metal hanger that holds the music box over the door inside. That thing was a pain in the rear end. Anytime anyone walked by the room, it'd go off singing 'Rockin' Around the Christmas Tree'. Everyone seemed to love it though, including the housekeeper (who I left it for, the day I flew home). I would not take something like down there again, but I was solo that trip and it was kind of nice as a security feature. No one could get close to my door without me knowing it.