Our Concierge experience was at Wilderness Lodge - however since no one else had commented about AKL- I can tell you what WL does.
Morning: Breakfast, something hot, something cold, plenty to drink, opportunity to sneak a few things back to your room for later
Lunch: While there isn't 'lunch' there are afternoon snacks, goodies and drinks.
Afternoon: Snacks: Trail mix, assorted candy (there were gummy worms one day), cookies, and I think I remember there being Uncrustables (PB&J)
Dinner: YUMMY there is always some type of hot food. We had the most amazing roasted pork in the lounge on our honeymoon! It was made with roasted sweet red peppers - very good! They always have alcoholic beverages, and regular soft drinks, AND my favorite Panna Acqua water - it's mineral water from Italy - I have a bottle in the fridge that I am waiting to open on a special occasion!
After Dinner: Desserts, Cookies, Baked Goods (Apple Crisp), wine, cordials, etc etc.
We think that staying concierge is well worth it in the off season times because it really isn't all that much more expensive - and you definitely get your $$$ worth out of it, since there is a fridge in your room to keep drinks, and you can take a plate back to your room with cookies etc to keep in your room or take into the park with you (in a plastic bag of course!) During peak season it is really expensive to stay concierge and really the level of service is lower due to the larger number of guests for the same amount of concierge folk to handle.
The nightly turn-down service with chocolate is a nice touch

Plus the friendly folks that greet you as you step off the elevator (at least at Wilderness Lodge) is a great 'welcome home' at the end of a long day! Plus their ability to handle dining reservations and such is really a great add on so you don't have to go wait in line in the lobby for the overwhelmed concierge there.
If you have any questions just let me know!
Once again - our experience was at Wilderness Lodge!
You can read concierge reviews online for all the resorts!