So If you don't care that there is potential that you could both end up sitting in Middle seats, than no worries... but because it's Orlando, I might suggest it, because after the A people (early birds) are called, then all the parents can preboard with small children, THEN the B group gets called. Not saying you would get a middle seat, but you could. I would treat yourself and spend the cash for it. And as someone suggested, it will be nice for you not to have to remember to check in while your still having fun at Disney. So if you didn't want to do it both ways, maybe just do it on the way home?