I love the new themes in Gmail! My favorite one to look at is the Candy theme. But I find reading my emails with it distracting. I’m currently using BubbleGum for my mail. ;) What about you?
You can view the themes by going to Settings and then Themes.
I’m using the Ninja one for my family email and good ol’ light blue for my own. I think I like the basic ones better, though.