I don't know if it's an option where you are, but we put cedar "hogfuel" on our personal outdoor agility arena (120 x 120). It's spread over heavy-duty landscape cloth. "Hogfuel" is basically shredded cedar. It's very fluffy at first, which many people don't like, but after a winter of Oregon rain, it mostly matts down to a sort of wood felt. It can still get "fluffed" where dogs run. It can be raked pretty easily. You could probably pack it down with a heavy roller (the kind landscapers use to smooth out newly seeded lawn areas).
It will support some weed growth but with the landscape cloth underneath, the weeds generally don't get a good "root-hold" and are easy to pull up.
Even when it's new, it's not really any softer or fluffier than some sand/sawdust mixtures I've run on. It's hard to get it perfectly smooth, but it's not any lumpier than most grass lawns. You usually start with about 4-6" depth which will pack down to 1-2" thick, over time.
We've had it for 5 years now. It does require some renewing (add more hogfuel). I've heard of some dogs having allergies to cedar, but the volatile oils evaporate after a few weeks in the sun. My Collies get shreds of cedar in their fur but it comes out easily; the border collie doesn't really pick it up at all.
Water drains through it really well, so we can run on it soon after rains, a real bonus in Oregon. No mud!
I've added a photo of our agility field.
Another alternative--I have a friend who used "decomposed granite" for her agility field--a lot like sand, but it packs down without turning to a hard-packed surface.
Deanna Lyons