> startups, research abroad, "choose your own adventure" style careers

I'd add scientific research experience. I had a professor who I worked for and gave me research experience. I was meeting with him 1-1 as if I was a graduate student of his at my top-25 undergraduate university. I also got a publication out of it. This gave me a huge leg up in my graduate applications for PhD, and it helped me determine that was something I was interested in to start with.

That sort of very personal relationship is much harder to find at the big state schools.