It's not your primary concern now, but you should really look into moving some of your live rock. You have it too close or leaning on the side glass, which you will be unable to access and clean later. Believe me, you'll go nuts because of it. Also, your LR is all stacked at the back, leaving absolutely no flow in the back of your tank. This is where all the garbage will get stored, lack of flow will cause it to rot and foul your water.
It is easy to browse this board for images of other tanks - you will see most are setup much more openly, with a lot of passages, caves and overhangs. That will give your fish space to hide when they want, but also give you place to put your coral on.
As for sump - I would never run a tank bigger than 30g without a sump. It's just so much easier and the equipment choice is much, much wider. Such a big sumpless I would actually call "unusual", and you probably don't want an unusual tank.
