I'm a summer intern (worked at a small tech startup in the Silicon Valley for about three months) and am planning on writing thank you notes to those who I closely worked with this summer (i.e. talked on a semi-daily basis about work).
I'm wondering, snail mail, leaving them on desks, or just sending personalized emails? The company culture is pretty casual (we wear jeans and t-shirts to work etc.).
edit: I'm thinking of sending these after my last day as a follow-up, after I've sent out a mass thank you email to everyone in my department. I'm also not planning to come back next summer since I've figured this is an industry I don't want to work in.