Yeah, definitely listen to "theguyadvice" and ignore everybody's advice on this message board (does he not see the irony in his own post?)...
Anyway, if you were to age grade your PRs that you included, your best is the 600. Your 200 is equivalent to a 1:25.8, so your 1:24 is clearly better than your 200. This is why I suggested focusing on the 4/8 and maybe trying out some 2s and 16s to see if maybe you improve on them with more racing experience.
Since the longer the event, the more important the training compared to natural ability, I would say that your lack of experience suggests you could be much better in the 400/800 than in the 200, since you probably can run pretty close to your natural ability in the 200 more or less instinctively. Your terrible pacing in the 600 suggests you could have gone even faster, lending more support to my contention that you should focus on longer distances, since your 600 is already more impressive than your 200 even with that terrible pacing.
But you could listen to "the guy advice," since he once ran a 400 time that doesn't come close to elite status (the world record over hurdles is as fast as him...). Or you could listen to any advice, since some of us on this board actually coach elite athletes (and weren't just athletes) and more to the point in your case, top age group athletes.
After you have run a few races, you can compare them with calculators such as this:
http://www.howardgrubb.co.uk/athletics/wmalookup06.html
This will allow you to decide for yourself which you are best at.
I will get back my suggestion to consider just doing which event you enjoy the most though. Your decision should be a factor of how much you enjoy the training, the racing, the group you would be working out with in that event, and of course also how much satisfaction you will get from what level you think you will compete at in that event.