Hello and welcome.
Well, I really encourage you to go read the race reports on different Ironmans at www.beginnertriathlete.com.
That is how I picked out the IM for me.
Really, picking an IM is all about personal preference. Sure, people say Florida is a great first time IM... if you like flats with wind and swimming in the ocean (with the possible threat of jelly fish- yes, people have been stung). I hate riding flats and I hate wind. So no thanks. I also did my research and it fills up QUICK. I wanted an IM where I knew I wouldn't have to travel to the race site just to get a spot.
Sit down and write down each of the possible races you might want to go to, and then start writing down pros and cons.
For me, Ironman Kentucky was perfect. No ocean swim, it's warm (I hate it when it's below 80 degrees), hills on the bike, flat run. YES! Perfect for me.
I was looking at Ironman Arizona for April 2008 (which is now going to be in November from here on out)... but I didn't want the bulk of my training to be in the dead of winter. Not to mention in 2007 they had horrible wind. No thanks.
So what's good for one person, is not for another.
All of this information can't be gathered or obtained in one thread on a message board. Read the IM reports. Think about what matters to you and pick yours.
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather, to skid in broadside thoroughly used-up, totally worn out, and loudly proclaiming: WOW WHAT A RIDE!!!!"