dunno if its been suggested, but Id look at the sportster nightster for a young guys first street bike - smaller engine, just as cool as the street bob - in fact, the look is a little more agressive - I just think would be a better first bike and still a 'solo rider' bike so it discourages passengers
On the side, you definitely get the 'cool' factor for even considering to buy yer son a bike - Just make sure he realizes the dangers - but the again they can kill themselves on the local halfpipe witha s kateboard too, so I dont get too wrapped up in the danger aspect, just needs to realize is all
Good Luck!