Agree with the above, esp. with FoxDad -- if you're coming from 55-80, 60-90 isn't a huge jump.
I'll add:
For a good catcher the big field is a great opportunity and be one of the few that can control the running game at that age. Plus you'll play on more fields with lots of foul territory behind the plate, so blocking becomes so much more important, along with the ability to get outs out of foul popups.
For pitchers, obviously control and velocity are more of an issue, and often breaking pitches that were devastating become very hittable on the big field. Any kid throwing a football change or slurve probably needs to learn to throw a real curveball.
The big field exposes slow runners and rewards fast ones. It's true that more grounders turn into outs, but quick guys still get to first a lot more often either by hit or by error, and quick guys who can bunt can get on a lot. Nothing more depressing than a lefty pull hitter lacing liner after liner to the right side only to see the RF throw him out at first base every time. Speaking of which, big arms become bigger. Nothing more fun than seeing a CF throw a kid out at first on a what looks like a base hit, or a SS getting the guy at first on a ball in the 5-6 hole.