Simulator looks cool so far, lots of potential in something like this. I assume that the haste proc actually works as haste although the heading says AP?
Not that I mean to overwhelm you with stuff but these are just things I would like to see if you have time.

-Improved Berserker stance/Unleashed Rage check box
-Commanding Presence/Solarian Sapphire check box would change Battle Shout AP
-Imp. Heroic Strike, DW Spec, Anger Management, Impale, Deep Wounds, and so on...
-Input mob armor rather than % reduction and add a armor penetration box.
-Mongoose
-Input length of fight, maybe then execute could be modeled as well
And to be really nifty a report at the end with a breakdown of things like actual crit rate, % of total damage, uptime of trinkets, ect.
EDIT: And a way that I don't have to put in my stats every time would be cool too.