outdoor arenas

I am working on building a proper outdoor here. Thinking 100 x 200. need to be able to rein, and run barrels and poles. TwoEyedChelly brought her horse here on Sunday and we now need a better area to ride in. Lol.
So my questions are, what size would you go with, footing type (I'm thinking sand as I can get it free and Wade has a semi to haul it with). Fence type, underfooting, lighting. Or anything else you can think of that will be helpfull. It is currently good enough to ride in, barely. Unless it rains, then it is pure mud.

I wouldn't go real heavy sand... ever ran in a foot of sand... GAWD, talk about wore out and pulling muscles... whew! Ours is 100x200, a full sized roping arena with boxes at the end and a cow catchy thing at the other end... which has sort of been made another breeding wall area...Ours actually is a little bit of a slant to help with water rain-off... I know, I know, but trust me I've rode in that thing so many times it doesn't bother me... probably not a good thing, but it'll sure leg one up.

Ours is just flat dirt, when it doesn't have grass all over it like it does now. Rick will take the tractor and not till it up, but sort of rake it, but he made this rake thingy that's real heavy metal with teeth on it that he puts a big tire on top of it, to make it sort of dig down....