Because of my prior running experience I actually started at week 4 in the 18 week training schedule.  However, I have still not chosen a marathon to prepare for.  So I started looking around for a marathons that was around the time my 18 week training would complete.  I found the Space Coast marathon and think it was the right one.  It is the oldest in Florida, and in my mind would have been fun since it is space themed.  I now have more purpose, and a goal in mind.  I will wait until later to actually register, but this looks like the right choice to be my first.