Hi-
If you can manage a jump of 40 points on your GMAT, I will recommend that you wait for a year Buck92 and apply next year. You are not completely ruled out this year though, and your chances at Georgetown and Vandy/UNC are higher than those at Duke/Cornell, however, with another year and an extra 30 to 40 points on your GMAT, you can take a shot at higher ranked schools( Duke/Darden/Stern etc. ) .
Ideally someone like you should have done the early bird for Duke. After the commitment round( early bird- when they expect you to withdraw from other places), they open the gates for everyone. This is when you will be placed right next to the 700's with 4+ years of work experience. Even if I discount the lack of work experience as you can showcase maturity of thought and leadership since you had been working during the Undergrad too, I still see GMAT as slightly on the lower side Buck.
Can you get a GMAT 710? If the answer in your mind is- YES! I will recommend that you wait for a year and then apply. You will be giving them Money, and two years of your life. Wait for a year Buck. You should be able to get better schools.