Haas, UCLA, and Stanford stay pretty similar. There will ALWAYS be a "Why MBA, Why Now, Why this school" essay, so start writing that first! It'll help you tremendously with every other school (you can pretty much cut and paste over 50% of that essay for many schools).
UCLA's family essay is new this year, but the leadership one is the same.
Haas has a few new ones, but most are the 250 word essays. The leadership one is generally there
try to prepare a 500 word optional essay for those schools that let you. I used one to talk about community service and extracurriculars, and was able to use it on all my schools except for Stanford (which did not allow optional essays except for extenuating circumstances)
Stanford will always have the "What Matters Most" or "What motivates you" type essay... start writing that.
I think that's it from me. Haas and Stanford's essays came out by August, so you'll have plenty of time if you finished drafts based on this year's essays already.