Honestly, size doesn't play a huge role in bmx bike sizes. Height does. I'm 5' 11" and ride a Mutiny Burlish with a 20.75" top tube. If you want a bmx, get a 20". A cruiser is just going to feel like a MTB like a Giant STP or something like that. I weigh about 260 right now, and i ride a little bike that weighs 22 lbs. flat. Most bikes will hold up just fine.