I think it is good to do what you love. A dinosaur theme would be good.
I considered my son to be like a teddy bear. So we did a teddy bear theme for his 1st birthday. And I got some cute ideas on etsy.com. For my son's 2nd birthday, Gymboree had a Surf Monkey collection, so I did a surf monkey theme for his 2nd birthday--it was a really cute cake with a monkey on a surfboard. And I know that it would be fun to do either a sports theme or a superhero theme for his future birthdays. At 2 years old, he loves his Batman PJs from Walmart, so I have a feeling that we are leaning towards a superhero birthday at the end of May.