Dude if I could travel at the speed of light, I'd literally... I was going to say visit other planets but I just remembered that you also said in your post some of the closer star systems are a few thousand/billion light years away. And spacesuits are expensive... But moving at that speed would be kinda fun. I'd be able to go home in between classes (home is around 3.5hrs from where I study) so it would be a pretty neat ability.
Keep making more of these science/physics based posts though.