Half or Full? I would look at a few things to decide this question. First off, what are your goals as a runner? If your trying to BQ and that is a goal in the future. I would recommend running at least one marathon a year to build your experience. I would also ask yourself how much time to you have to train? A half does not require as much time as a full. Some try to train for a full and they have way to much going on with life, either kids, volunteer activities, job's or other hobbies to put the training required for a full. If you have the time to focus on doing the training, then doing a full is much more enjoyable.
If your main goal is to stay in shape, or you just love to run and are not worried about how fast you are, the Half is a perfect distance. Focus on setting a realistic goal to improve your time in the half. When you feel you have reached that point and want more, then it's time to look at the marathon and BQ if you have the time to train ;-)
Good luck, what ever you decide. The first step in any training plan is to sign up for the race!
Half will allow you to train, stay in shape, less risk of injury, and you will enjoy your trip more...just my opinion :)