Going into spore, I was all up and going "I'm gonna make this, and then I'm gonna make this!", but once I actually got started playing, I found it a hell of a lot more fun to just follow logical evolution. (Not making any incredibly extreme changes, just having my creature grow a little at a time.) My only goal was to have a humanoid creature by tribal phase... which I did.
My first creature was a carnivore, a praying mantis sort of creature that with four arms and reverse jointed legs.
My second creature was essentially a mix between a boar and a tauren. It was an herbivore all the way, but damn they were good in a fight. (5's all the way across the board for melee abilities, and a crap load of health.)