Other alternatives that look great, fill in space, and stay bushy are the needle leaf java ferns. Super easy to keep too.Hmm.. I actually think jungle Vals would look great in your tank (fills a lot of space but it doesnt grow super wild) or hair grass montevednesdifsdfas (can't ever spell this, the longest type). I think you'll want a stem plant that is long, leggy and flow-y, otherwise it will start creeping into the driftwood (unless you're okay with that).
Or a little shorter you can try Blyxa Japonica around the base of the hardwood.
I know that it seems a bit odd, but I would move the rocks down away from the wood - in other words, provide some space for mid ground plants, otherwise they will just grow over and obscure the rocks.
Something like this comes to mind. Of course you don't have to fill in the right side.