What would be a good beginner street bike?

Dependant on your bndget really, go for something naked, like a Bandit 600 or Fazer 600, cant go too wrong

At your size and weight, your inseam (leg length), is going to be more important than your weight. You will need a full size bike with standard frame, no "low"models, and you will probably be more comfortable with forward foot controls, although this is not essential. Visit all your dealers first, Honda, Yahama, Triumph (if you can find one) and don't forget BMW. Look at cruisers and sports tourers first, for example the Harley Davidson "Dyna" series or the BMW 800ST or 1200RT (sport/road tourer). Sports/road tourers sit a bit higher than cruiser, and for your height, they might be ideal. They are not for everyone, however. Even they are technologically advanced and are easy to ride, these "Beemers" do not look or sound like many people's vision of a "true" motorcycle. Forget a 250. Great for a motorcycle safety course but too underpowered to push 227 pounds along with highway traffic, for very long, anyway. "Keeping up" with traffic very important for a motorcycle. At first, almost any bike will be a bit intimidating. But once you get the hang of it, the extra power, say 1200 cc and up and the extra weight will give you a solid ride with good stability and ability to maintain highway speeds comfortably. PS Master single rider techniques before you even think about taking a passenger on board.

Could try a Suzuki SV650 - a lot of fun, cheap to buy and insure and can sound awesome. Guys your size should really be looking at an adventure type thing like a GS1150 or similar. Not 'street' perhaps, but certainly more confortable!