"Put something like this up in each classroom or a large one in a hallway to show off work throughout the summer." -- We made something a little less fancy than this with string, ribbon, thumb tacks, and clothespins. The kids loved showing off their work, and the parents loved getting to see everything too.
Quote bubbles in frames, use a dry erase marker to write funny things your kids say. When you are ready to switch the quotes, have the child take a picture with their quote and make a photo book of quotes... seems like a cute idea - not sure i would put in the effort to go through the entire process but am definitely documenting quotes from my children (whenever i end up having some) :)
Write notes back forth with your child. Leave it on their bed, when they have a chance, they write back and leave it on your bed. How neat would it be to have those notes to look back on? I can only imagine how special this will be!