I have an A200 with the Sony 75-300mm lens and it's okay. But I started doing more aviation photography and realized that at
SAN I'm pretty far away from the planes and requires me to be at the 300mm length which loses a lot of the sharpness. It also has a pretty slow focus. While it's still pretty good for the price I'm still looking at the Sony 70-300 G Series lens, I tried it out the other day and it really makes a difference. I've kind of learned that you really do get what you pay for with Sony lenses. I paid $150 for this one and the quality of the images at long ranges reflects that price. Now the lens is great up to about the 200mm range but past that it gets really soft.
This is a really great lens also but it's a very steep price increase compared to the 300mm G series lens I was looking at.
I think it really depends on how far away you are from the planes. I'm about 350 yards away at my airport and a 200mm wasn't enough for me. But it all depends on where you will be taking pictures. Where I am is not the most ideal location but after 9/11 it's not like i can just sit next to the runway without going to jail or something.
It all depends on what your budget is, if you have the money I would suggest looking more towards the G series lenses.