Avalanche wrote:

Is there any reason, other than it perhaps gets kicked around easier,
that sand (clean, of course) sand won't suffice?

None that I know - why do you think they were originally
called "sandboxes" instead of "litter boxes"? And if your
cats go outside, they're perfectly happy to use your kids'
sandbox, if not prevented! (Or your neighbors freshly
planted garden.)

Any particular benefits to more expensive litter? Tho I've had cheap
dusty litter.

The clay litter doesn't track as badly (in theory), retains
moisture better (no totally saturated sand, with puddles at
the bottom of the box), and (at least in theory) controls
odor better. The first cat I had, when I was a kid in
Minnesota, we used a box full of sawdust - more satisfactory
than sand, and I don't think they even SOLD things like "cat
litter" way back then.

I doubt the cat really cares, so long as there's something
to dig in and use to cover up afterwards. The one exception
is highly scented products designed to mask the odors - cats
often find the heavy perfume offensive, and won't use them.
I've been using clumping Fresh Step Cedar for some time -
the cat seems content with it, and it really seems to
prevent litterbox odor for some time, without changing it.
(I just add a bit, from time to time, to replace what has
been removed with the daily scooping.) I've often gone as
long as two months without a complete change of litter.