I wouldn't go with the ninja (big one, not the little toy one)- it's a lot of bike, expensive if you bend it and not really the easiest to ride effectively. Plus, lots of brake, quite easy to catch yourself out- it's bad enough having a noob moment with basic brakes. You're pretty likely to have some sort of bump on it, and even dropping it at walking pace will damage a lot of plastic. Are you doing an MSF course or similiar?
For the discerning US buyer- Suzuki SV650S. Lots of 'em about, cheap, very tough, great spares availability, easy to work on, easily uprated too. Very nice engine, not too much, not too little... Engine braking can be a wee bit unsettling for the noob but balancing that is that it's got drive everywhere, you don't need to keep it on the boil. Ropey suspension though, and not especially well made. Basic brakes that work. But it's the price, availability and indestructibleness that makes me recommend it.
I'm biased, I love my SV, but it's got practically nothing in common with a standard one now anyway... But the basic package is just a really nice, usable wee bike. The suspension's pretty poor but that won't trouble you in the early days, and it's not hard to upgrade (just check out some of the SV race bikes, or even the road bikes in the SV Of The Month section on SVrider.com- and I'm not just saying that because mine's in there

) And the residuals are good, you'll
always be able to resell an SV easily.