Great info James. I am beginning my build for an olympic distance triathlon in September.
For me running distance isn't overly taxing on my aerobic system it is hell on my tendons and ligaments. I have to build up to longer distances if I don't want to be in pain the day after the run. I ran 4 miles with my sister last weekend and it took 4 days to recover.
Allen the best advice I can give you is to go to a running store and have them help you with fitting. Doing that changed my comfort level completely. If they know what they are doing they will check you for over / under pronation and reccomend a shoe accordingly.
I weigh right at 190 and I agree with James whatever you do for training I would stay away from a light weight trainer or racing flat. My personal favorite is the asics cirrus gel. It is a nuetral shoe with good cushioning. I have 3 pairs. the other goofy thing is that I use these laces that are like bungy cords and I just slip my feet in and it adjusts the pressure accordingly. I think they are called lace locks. With laces I get hot spots on longer runs.
What we think, or what we know, or what we believe, is in the end, of little consequence. The only thing of consequence is what we do. -John Ruskin