I have a reward stay coming up in two days and my first name on the reservation now is listed as "EG" in place of where my first name used to be. Does anyone know what this means, and would the hotel have changed this for some reason? On the other hand, my room now shows as an Ocean View (a double upgrade).

First, I would not assume that what you are seeing is correct, especially about the double upgrade, unless you also saw a further point deduction from your account (over and above the original award cost, for the upgrades), and second, I would call first Marriott Rewards to inquire, writing down the reply, then Marriott rez to inquire, writing down the reply, and finally the hotel to inquire, also writing down the reply, each time with the name of the person who gave you the answer.

Then, assuming that you will have at least two, and possibly three different, conflicting answers, I would call Marriott Customer Service, ask for a manager, explain the problem, and insist on a resolution, in your favor for the most beneficial of the answers (any customer should be able to rely on what a Marriott associate informs them to be the facts, because after all, if we can't rely on a Marriott employee to be definitive, then what is the point of those employees being in positions of authority or customer contact?)

hotel's will typically use "codes" to make it easier to identify such things as reward stays and which folio to allow charges to etc...however I honestly wouldn't worry about it

EG = Elite Gold ?????

That's what I was thinking as well, but found it odd that I've never seen my name changed on a reservation before. Welcome to the resort Mr. EG...

could be but the code for Gold Elite is too common to need another code