If I were to die tomorrow, I'd regret not doing everything I wanted to do sooner. I've done a lot of the things I've wanted to, visited much of the world I want to, but there's still more. But for now, I'm assuming I have time left.
And people crack me up with the "no regrets" Utopian cliche. I don't believe you can live 30+ years and not have a single "maybe I should've done that differently" moment.