there's nothing wrong with the rocks you have, but i would definitely suggest mixing them up a bit.
also, maybe make just one big off-center pile of rocks instead of the two separate piles. (if you're worried about them falling you can get an underwater fish-safe epoxy from drsfosterandsmith.com)
Go for 2 asymmetric groups of rock, mixed as above, left and right of center, leaving a hollow cleft or valley off center. Put the driftwood in or near the valley so that the tip of it is roughly 1/3 of the tank's height from the top and 1/3 of the tank's length from on side or the other.
If you want to know why the roughly 1/3 matters, check APC, search for Aquascaping 101 or just Google "Phi golden ratio" for a shorter answer.
Also - lay the heater along the bottom or go vertical w/ it in a corner. No reason to look at that.
Mix the different rock, set them up and lean them against one another. That'll give you more height, crevices, nooks and crannies, perhaps a little greenery. I get my artificial greenery at places like Hobby Lobby or Michael's Hobbies. You can find unusual plastic greenery and a fraction of the price. Natural plants add a nice touch too, while they last. You have a nice rock collection maybe just re-distribute them an unorganized manner. Enjoy your work in progress!