We filled the bookshelves with books and stuffed animals from books. We hung book cover art and various illustrations on the walls as well.
Bedding: Carousel Designs
Crib: Babi Italia via BRU
Dresser: Simmons Kids via Buy Buy Baby
Wall Shelves: Crate & Barrel
Floor Lamp: Pottery Barn
Our friend made the gorgeous bird mobile for us, which hangs above the glider. I also love that all of the books on the bookshelf have inscriptions from friends who attended my book-themed shower and brought books they love.
It was more fun putting this room together since the theme was something that both of us loved. I'd say to try and incorporate a shared interest so you can both be involved.