I have not found a way to change the stock keyboard, but Swype Beta has a bunch of skins/themes out there. I still use the stock as I like the ability to use the stylus.

 

I replace my contacts and dialer with Go SMS and Go Dialer.

Many themes there and excellent functionality.

 

Smart Keyboard Pro has several colors/styles.

 

replacing the keyboard will do nothing to change the dialer.

Though I may have gone the other wauy in this one and assumed by saying phone that phone app was meant.

I can highly reccomend Swiftkey Tablet X as a keyboard replacement. There are many themes and the auto suggestions (not necessarily replacements) are second to none. If it knows I am texting the office and I start "I wi" it offers "will" as the replacement followed by "be", "a", "little", "late", "ring", "if", "it's" and "urgent" all at one press next word completion.

Just for general conversation it has learned my nentence composition pretty well.

If I wasn't so dead set on teaching myself to write properly again by using the handwriting element of the built in keyboard that would be my next choice. I don't say that lightly. Me and Swiftkey came to blows but their prediction rocks and they do a good keyboard.