Awesome question!!! It's sort of hard to answer though.
I know I love it when my girlfriend is being all cute and getting me things without me asking for it, but I don't know if you could classify that as being romantic. I think being romantic is more often than not something guys do for their girlfriends, and that's when some of us go all out. Flowers, Chocolate, Presents, Home made meal you name it, we've done it, at some point or another.
I don't mean this in a horrid way but I'd say guys are more relaxed than women. We love the little things more than anything else, at least I do. When you have to go out and do groceries and you bring back his favorite bag of crisps, or his favorite drink, we really appreciate and it's a little thing to do, but it goes a long way. Us guys like to know that you're thinking of us too.
So make the small thing count.
My girlfriend bought we some Japanese candy once, something I wasn't at all expecting and to be honest with you it made my day. I loved to know that despite not being with me she was thinking of me.