I've done a room with murals (pink bedroom below), yes they have a somewhat whimsical feel to it, but in this day and age, practical design seems more appealing.
In the end, this is what my baby's room looks like. Now at six months (they grow too fast) he knows to look at the right sticker when I say "where's the monkey?" or "where's the elephant?" Still working on the other animals, but hey, he's only 6 months right?