I'm 6'5" tall. I have to have a King, else my feet hang off the end and it's terribly uncomfortable.
The funny thing is, my wife is 5'4", but since we got married, she's totally gotten used to the all the room that a king bed provides. Now, when we travel, she bitches about having to sleep in anything smaller (including the Queen-sized bed that her parents have in their guest room).
My advice to you is to get the biggest bed you can afford, and fits in your bedroom. Life is too short to sleep in cramped conditions (not to mention that you'll enjoy a higher-quality of sleep, and by extention, tend to be happier and have more energy when you're awake).