All ideas posted so far for enhancing your tracks are, er, sound. Suggestion, try just putting some slight reverb on your master buss. Or some other effect. See how it helps, or doesn't. Maybe a bit of a short reverb, a long one, I don't know--it's your work! Just try some things on the main out buss. (If you're not routing everything to a master buss, then add a buss and route all the tracks to it. Easy, and a good practice work out.) Just try some stuff. If you are uncomfortable with routing to busses and such, well, you shouldn't be. They are your friends and are great ways to add all sorts of effects, (good or bad, you decide). You've got the keyboard/midi chops, you've got plenty of ideas judging from what you've done so far, now work on becoming a Sonar ninja.
Here's another idea. I posted a complete Sonar project to a published work, you can read about it
here. It's not exactly like your work (good thing, we'd get into a fight over rights!), but not exactly unlike it either--lots of synths, etc. I use a fair amount of effects and EQ. Maybe you can get some ideas from looking into that project--that's what it's posted for.