My problem with circles is that it doesn't limit, enough, the area from which the throw should happen. The Trapezoids are good, in my opinion, because they allow multiple angles to be taken towards the desired launch point and don't make people step off the sides of pads but they also limit the launch point to what the designer has designed. The trapezoids don't have to be very pronounced to make a difference either. Maybe 5' on the front and 6' at the back and 12' long.
One other thing that can be really good to save a little bit of money in the budget (so we can use it elsewhere
) is only making the full big sized pads on the bigger holes and the holes that are around 300-350 or less can have a smaller (though still spacious) version since those holes don't require as big of a run up. Just a thought.