So if I want to store a list of items (such as a bunch of instances of a class), what's better to use: tuples or lists? I understand that lists are mutable, so what are the advantages to tuples?

Tuples are great for constants because you won't accidently change them, they're also faster and use less space then lists, iirc.

Zonr is right, that is what a tuple is for! You want to preserve the integrity of your data here.