Honestly, I've had great luck with the 3M adhesive hooks. Just buy one that lists an appropriate weight limit for your wreath, or go with the biggest one they've got since wind and weather will add more load on the hook.

Why drill when tape will do?

Thanks for the reply. My siding has a wood grain texture, so I felt that would compromise the ability for the command hook to stick. I would up using two black cords (they were almost invisible against the dark grey siding) that I ran through windows above and tied them off to small cleats on the inside.