Well, find out what you want. A sportbike or a cruiser. That alone should decide your ride. I'd get the 500f since I like sportbikes.
The valve adjustment. You can probably check the valves yourself, then in the rare instance they need adjusted, you take it in and have them do it. Your bike is already dismantled so the charge shouldn't be bad. I'd like to be able to do it alone (just like you I'm sure) but its very risky on DOHC bikes. On a TTR125 dirtbike it was stonecold easy.
Take hal's statement with a grain. Its better and safer to learn on a small bike first. Then when you outgrow it (and master it) you'll take alot better to the added power. Again, its fun to stick the cane to a small bike and scoot around. But too big a bike when you're starting out can be hazardous. Trying to balance, hit the turn indicator, watch for traffic and have to worry too much about the throttle because your wrist isnt smooth enough (yet) to gradually roll on instead of being a bit jerky.
cmon hal, through a newb on a liter bike and you can count the day to the fall. I had a good riding buddy who got an R1 (while I was on a 600 learning/focusing on cornering) all he knew was wide open on the interstate. Well, I took him to some twisty roads one day. We just started our ride and was about to hit the first good turn when he flew by me and didnt know the first thing above leaning the bike over, and well, he kept going straight into a fence. He was ok, but the bike wasnt.
Anyway, after I put 40k on a 600cc sportbike I learned that it was a big bike for the street. These RR (race replica) bikes are made for the track. They throw some blinkers on them and call them street legal. I did try to trade my 600 in on a ninja 250, but they wouldn't accept. That little 250 is all you NEED for the street. Its handling will surpass its power, thats what you need for a beginner and all you should desire as a veteran STREET rider. IF you're not into breaking the speed limit (by more than a little), your Suzuki should be fine. IF you want to lazily putt around then get the Vulcan. Also, make sure you can lean forward all day if you want a sportbike ( I love it and wouldnt have it any other way, but I'm under 30).
Now if you want to tear hide everywhere you go and take any corner as fast as you can, get the 250 ninja. Its less likely to get you into trouble. And if next year you find yourself ringing its neck for every last available hp, then sell it for a few hundred less than what you bought it for and get a 600 I-4 and be on your way.
For me, I had a 97 YZF600r, then got a 05 YZF600r and now I want a bit more top end rush so my next will probably be (hopefully) a CBR F4i or 600RR if the F4i is too old by the time I get to it.
Good luck!
