I've been able to return before-- as long as it's never been used. Given, I bought something at the LV in the Forum Shops at Caesar's and returned it to the LV at Wynn because it was closer to my hotel room (Las Vegas).
I think you were able to do that b/c they were both standalone LV shops. The ones at dept stores are on different systems. For instance, I can use my Saks card to buy at the LV store there but obviously not the stand alone LV store. That's why you can exchange but not return due to the fact that the different computer systems can't refund your money. HTH
I would feel very awkward doing that. I wouldn't do that to a Nordies or a Macy's or any department store - I always return it to the same store where I bought it. Maybe I'm weird or funny or just plain shy!
The return policy is 14 days with a receipt, 30 days for exchange with receipt. It doesn't matter if the store at which you bought is different from the store at which you return. I exchanged a wallet I bought in HK with a wallet at the boutique at NM. I had a receipt, so it was no problem. However, without a receipt, they will not do anything for you.