I've always been digging UI design and addon functionality (still a noob when it comes to LUA) but I know a fair bit.
Here's a couple tips for you,
- Sometimes it's best to steer away from the "bold" look, especially graphically intense UIs (They tend to slow down your computer a lot and could potentially even block off parts of your screen, where you know, there could be fire there for an example).
It also tends to be distracting if there's a lot going on with your user interface (some people like that, but usually you can't go wrong with a nice minimalistic look).
- Also, you mentioned you were using Dominos. Why not try and hide a few bars (but they're still active/in the background and keybinded) for spells that don't have cooldowns, or simply keep a cooldown watch addon (for an example, ForteXorcist)
Doing this takes a bit of practice at first since you can't see your spell icons, but can also be beneficial at the same time - it makes you look elsewhere rather than having your eyes glued on your action bar
- This site provides a lot of great ideas for UIs: http://www.wowuigallery.com/
you can either choose to replicate them with your own favorite addons, or of course download the packs that makes your life a lot easier :)
- As for the macro, this could probably work, but you'd have to hit the button twice to work
(Blizz disallowed cast sequence macros.... For obvious reasons)
/castsequence Frost Nova, Blink
- I suggest checking out this site as well for more macro ideas: http://www.arenajunkies.com/macros/mage/
Hope that helped.