Here are my thoughts from having done it in 2011 starting March 29th. Lots of other good community gear lists to look at on here also.
A few things I am still unsure about that I would love some insight on are:
Most importantly I need to decide on a pack to use. I USED A MLD EXODUS TILL DAMASCUS (too much room) THEN A MLD BURN ALL THE WAY TO KATAHDIN. If i did it again - I WOULD USE EITHER A 2012 GOSSAMER GEAR GORILLA, A HMG WINDRIDER, OR A ULA CIRCUIT or OHM. Loved my Burn - but had a hard time fitting bulky resupplies for 4+ days into it, and found that my shoulders got sore with weights over 20 lbs.
My shelter will definitely get the job done but I am considering some tarptent type of options. IT RAINED AND WAS COLD FOR THE START -- USED A MLD CUBEN SOLOMID W/ SUPERLIGHT BIVY and was glad to have the protection. Shelter will also be crowded at least for the start, so having your own shelter is a great idea. Maybe a TarpTent Moment or pyramid shelter like a SoloMid, unless you really want to go minimal for protection.
Replacing the Marmot Essence and Arcteryx rain pants for frogg toggs dri ducks? I started with Marmot Precip pants and an EMS rain jacket for the cold wet beginning...and once I hit hot weather past Damascus I used just a DriDucks jacket for the rest of the way. I'd keep your Marmot and Arcteryx till it gets hot out (past Damascus...I swapped at Pearisburg) then go for your Dri Ducks.
Go with an alcohol stove instead of my snowpeak canister stove? I started with an alcohol stove but once the hot weather hit I went stoveless for the rest of the trip.
Thinking about one more light layer to be worn while hiking when it is still a little colder. Either the Patagonia hooded Cap 4 or the Houdini wind jacket? I love my Houdini and hike in the cold weather with it all the time.
Lastly, still trying to decide on which guidebook to get. 100% get The A.T. Guide 2013 from AWOL (easier to use on trail than the ATC Guidebook, and the Databook is useless for actual hiking IMO).
Any tried and true lightweight digital cameras? I used a Sony TX-10 for the A.T, the LT, and the NET and its still going strong. I liked having a waterproof, freezeproof style camera so I could be taking photos when others were not due to weather.