luck*
I would try and get a CLI on your Walmart. If approved, let your CR's update and get your util as low as possible. It still might be a stretch on the revolver.
I applied yesterday for the AMEX BLUE. My scores are in my sig, yours are just like mine. All I had was 1 secured $200 Capital One Card. I did get 2 other approvals, Discover.It and Chase Freedom, both pretty decent limits, but I don't think AMEX could see those just yet. Go to the cardmatch site to see if you get one to pop up. Amex didn't pop up for me, but still able to get it.
Also if you are due for any CLI's I would ask for them if AAoA is 2.5 surely something is due for an increase. 
Also, your CS are over a year old; any idea if they have improved?
Forgot to note, my AAoA is between 8-12 yrs depending on which report you pull. That could have helped my case.
I'd listen to Lexie and the rest on their suggestions. Good luck!
According to SW they are pretty much the same. 
Also, I just updated my sig to reflect my CLI from BofA last month.
I would recommend apping for a charge card now. Then apping for the revolver you want come 1/2014 for backdating.
@MissCredit9 wrote:IMO get your utilization down to no more than 5% preferrably with a balance only reporting on one card. That should increase your score slightly and put you in the best shape you could possibly be in moving forward to apply for AMEX. I have seen approvals with old baddies, but I believe it is in your best interest to appear pristine in all other aspects. Best of uck if you decide to app!
+1 Yes, if you do move forward applyign to Amex make your credit report as neat as possible. Get any softpull CLIs you can, get your util down and only show a balance on one card. Your on the borderline so every point counts. Others have mentioned getting a charge card first to get your foot in the door. Charge cards are easier to get, but I am a big proponent of only getting what you need. That being said with your current scores I think its going to be tough getting a revolver but you never know. By way of comparison I applied for an Amex charge with a score of 699 and was turned down and they claimed my score was one of the reasons! In reality the main reasons were no open revolving accounts reporting and having had 3 recent inqs on TLs that had not appeared yet.