I planted mine in rows. Row of apples, row of peaches, row of pears, etc.
Some are dwarf and some are standard size trees so the spacing between the trees are different.
Therefore, they line up along one axis, but not the other, giving it a little bit of a random look.
Mowing along the rows is easy. I tried mowing across rows and it was haphazard; not straight at all.
Also, mowing under dwarf trees is a bit of a pain because of the low branches, I can trim the low branches off the standard trees but not so much off the dwarf trees.

Prince Igor

Thanks for all the tips guys! These are teeny barely trees, so we've decided to put them in pots and let them grow a bit more before putting them in the ground. Still not sure how I'm placing them all, but we have time to figure it out.