The Home Depot stuff is way too thin. It will flex and bend when you try to write on it.
We got a bunch of 24" X 48" X 0.375" sheets from Online Metals (ironic, I know) and hung them up everywhere. They were a bit pricey and you could probably do with thinner but they look and work great.
Edit: Just for info: Lexan is a brand name for polycarbonate plastic sheets. Plexiglass is acrylic. Lexan/polycarbonate is much harder, scratch resistant and more or less shatter proof. Plexi is soft, scratches easily and snaps into big jagged shards when bent too far or hit with something.
We got a bunch of 24" X 48" X 0.375" sheets from Online Metals (ironic, I know) and hung them up everywhere. They were a bit pricey and you could probably do with thinner but they look and work great.
http://www.onlinemetals.com/merchant.cfm?pid=7459&step=4...
Edit: Just for info: Lexan is a brand name for polycarbonate plastic sheets. Plexiglass is acrylic. Lexan/polycarbonate is much harder, scratch resistant and more or less shatter proof. Plexi is soft, scratches easily and snaps into big jagged shards when bent too far or hit with something.