How about an assembly inviting local vets to come and talk to the kids? Maybe even some vets who might have attended your school...or more likely, the local high school.
A local high school has a full day of speakers in the library and a three-day display of their memorabilia and stories...VERY well received. Could be scaled back for elementary school.
I know there are a lot of veterans at VA hospitals, you could always go there with a group of children, maybe even with their pets, and do something cheery.
These places always need magazines, it would be easy to collect some and take them in.
I frequent the local VA hospital with my dad who is a retired vet. The proud military bearing of the older vets is very touching!