my main dps macro on my shamans:

#showtooltip Lava Burst
/use 13
/use 14
/cast Elemental Mastery
/castrandom Lava Burst,Lava Burst,Lava Burst,Lightning Bolt,Chain Lightning


yes it would be smarter to save the trinkets and EM for "clutch" times but this lets me never, ever forget to use my trinkets and EM which I tend to do... a lot!