Jason Dykstra, sure. I'm currently working on doing my third property as a double-closing -- purchasing and then reselling to an already-identified buyer either on the same day or within a week or so from the date that I closed on my purchase. I had a fourth one under contract previously, intending to do the same, but didn't find a buyer so I canceled my purchase agreement with the seller.
So far, I did all of those on the purchase side with a pretty straight forward, one-page purchase and sale agreement that identifies my LLC "and/or Assignee" as the Buyer; generally has a latest closing date that's a few months out into the future (to account for any unknowns with clearing title on the property, finding a buyer, etc.); and includes standard language that Buyer retains the right to cancel the sale agreement any time for any reason.
I have not, so far, done a separate Option Agreement with the Seller; although, I have thought about doing so. It's been my general impression that a purchase and sale agreement structured with the elements referenced above essentially serves the same purpose for me, in that it allows me ample time to find a buyer; it should allow me to assign the contract if I wanted to (although, I haven't actually done an assignment yet, having double-closed each of them); and it allows me to cancel the contract if I choose to (which I did one time, so far).
On the resale side, I've used a very similarly structured PSA, but with a $500 earnest money deposit added; the Buyer's right to cancel any time for any reason removed; and perhaps most importantly, a Contingency clause added, stating that, "This contract is contingent upon Seller successfully purchasing the property, which Buyer and Seller agree may not have occurred by the time this contract has been entered into." In other words, I can't sell the property to my end buyer if I ultimately am not able to acquire the property from my original seller; and my end buyer can't hold me accountable for anything other than returning their earnest money deposit if it comes to that.