Some good advice already in this thread but will put in my .02 cents.
My plan is to get essays reviewed by 3 sets of individuals:
1. Person who is intimately familiar with you and who has no trouble taking you to the cleaners. In my case, my wife who can point out if the story makes sense. Whether there are other stories I should be considering, etc, etc. This is a content discussion.
2. Person who understands the MBA rigmarole. In my case, I have some colleagues at work/people associated with MBA programs to read through the essays to see if it paints the MBA story. This is an important step and I think can be valuable in pointing out logical inconsistencies, inadequate detail, and a lack of a cohesive narrative.
3. Finally, I have lined up a previous boss (English PhD) to work through style, grammar, flow, etc type issues.
The bonus review is from students who have already been admitted to the program you are applying to or alternatively someone who has been part of the Admissions process at your chosen program. Hopefully, the GMATClub community will continue to do what it does best and help each other out!!
However - remember to trust your gut. Complete overhaul of essays which leave devoid of personality and a certain rawness wont make for great essays. This is advice from a good samaritan at GMATClub who was generous enough to read my outlines.