Internship with a US senator?

How do colleges(top ones especially) view such an internship? Does it help significantly or is it somewhat common? If I were to be selected as an intern, it would be for NY Senator Gillibrand.
I’m curious as to if this is worth pursuing.

It’s fine. Being an intern by itself generally doesn’t mean too much. It’s what you do with that internship that matters the most.
If it’s a very selective process, then perhaps just saying you interned for this senator might help.