How do I get an enum as a string?

Probably the easiest way would be to implement Display by calling into Debug:

impl fmt::Display for Foo {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{:?}", self)
        // or, alternatively:
        // fmt::Debug::fmt(self, f)
    }
}

Then you can use to_string() to get a String representation:

let s: String = Foo::Quux.to_string();

If you have many enums which you want to print, you can write a trivial macro to generate the above implementation of Display for each of them.

Unfortunately, in Rust reflective programming is somewhat difficult. There is no standard way, for example, to get a list of all variants of a C-like enum. Almost always you have to abstract the boilerplate with custom-written macros (or find something on crates.io). Maybe this will change in the future if someone would write an RFC and it would get accepted.