I'll give you a choice or two. One, is that a friend of mine just purchased a 2001 Yamaha R6 as a first bike. Now, he said he has riden before, but when we went to the dealer to pick it up..he had an awful hard time getting it to move. Point being...he didnt know how to ride it too well. So one of the salesmen drove it home for him. NOW, after driving around his block here and there during the course of the day(not all at once) he had the BASICS down packed. He's roughly 6" 170lbs and he fits pretty good on it. Since then, he's ridden it almost every day and hasnt had any problems as of yet. Now, I just bought my first bike, but I purchased a 750 ONLY because I got such a hell of a deal, I couldnt pass it up. That...and I'm 6'4 200+lbs and I didnt feel real comfortable on a 600 MAINLY being the one bike I wanted...the Gixer 600. I believe that the Gixer is a race ready bike being its a Supersport(?) street bike. For the class, it has a good amount of power. But I've also heard that its not really intended for the taller rider. I know when I sat on it..I looked huge and didnt feel AS comfortable as I did a bigger bike. Only reason being is because with my height comes the bigger shoe size and where you place your feet to shift and break being that height with a big ass foot wasnt going to happen for me at least. But I've heard that the Katana(though I would never buy one) is a great beginner bike with a good amount of room. And the Gixer 600 and 750 is the same size frame, so dont consider that if you think of going to a bigger class with the gixers. I also started of riding with my bike truly for the first time. I've rode a ninja 600 but only for a few days to test it out. It's been about 3 weeks and I've gotten pretty good with my bike and driving in general. But I would also recommend taking the MSF as well because it will teach you alot. Taking it BEFORE you buy a bike...well, I dont know many people who have. Good luck and ride safe.