If you're looking for a 1-2 day assignment to celebrate Veterans Day and poetry, here's a good one. While it's not an entire poetry unit, it focuses on four main poetic devices in order to create a poem that thanks veterans.
The hope is that students know someone from the 20+ conflicts listed, but the list also provides a context for the poem, since most students would center their point of view on what they know rather than the experiences of the vets. This part requires group work, online access, or some teacher guidance, since kids likely won't know off hand where the Bay of Pigs is located. Use the Wikipedia link on the bottom of the Google Doc version as your key (or delete it to make it more challenging for students).
The framework provided includes seven required elements for the poem itself, along with a poem written by myself. You can view the poem here: http://satisfamily.com/relationships/connections/345-positivity-portait-ray-ost
If you're sick of assignments that just tell kids to write a poem about their feelings and do not help them to figure out how it's done, this is a good start. Change it a little for Memorial Day, Patriot Day, or Armed Services Day. This also works well if you are studying war or a war novel.
Because poetry can be very subjective, I would use the required elements and give the students a length to write, maybe 10-20 lines. Or not, since five lines of The Ball Turret Gunner is plenty to get the job done. Just avoid a Charge of the Light Brigade epic. If you are planning a Veterans Day program at school, then this is also a good guide for short pieces students could read at the assembly that focus on the veteran rather than the student.
This assignment download is linked to a Google Document that can be copied and edited by students. Or you can rework it slightly as a handout in the classroom. You can meet several ELA and social studies standards in one short worksheet. It's being used for grades 5-8 this year, but it can certainly work with high school students.