If you are going in 2 weeks, you should not be going at a time that is typically very busy.
By doing things like going to MK early (like when the park opens), it's possible to ride everything in Fantasyland, plus a few things with very short wait (like 5-10 minutes). This is true even in busy times like Spring break. Knowing where to be and when helps you avoid the crowds in the lines and also just generally out in the park. By the time the park gets busy, you will have spent a fair amount of time in the park and will probably be ready to go back to your resort for some rest and/or swim time.
I agree with the others that Fastpass is better for those attractions with it, unless you need some special seating for shows. You can send someone else in your party ahead with all your park passes to get Fastpasses. Then, when it's time to use the Fastpass, you can just enter the fastpass entrance. It's very predictable.
Because GACs are not meant to shorten or eliminate waits in line, you may not have the same experience using the GAC, even at the same attraction on the same day. It's possible that you may go in fairly quickly, but you could also be given a hand-written sort of Fastpass and asked to return at a certain time to the Fastpass entrance or somewhere else. So, if the attraction has Fastpass, it's more predictable to use that.
ALSO, using a GAC or a stroller as a wheelchair can sometimes even mean a longer wait. Some places this is especially true are Small World at MK, the Safari at AK and Spaceship Earth at Epcot. On our last 3 trips, we went on all these attractions seveal times during the trip. For Small World, at the time we went, the regular line had a posted 15 minute wait, but people were basically walking in as fast as they could and some boats were being sent out 1/2 full. So, the 15 minute posted wait was not accurate at all - the actual wait time for people entering the 'regular' line was about 5 minutes - the time it took them to walk from the entrance to the boat.
Meanwhile, we were at the handicapped entrance. We waited over 25 minutes - and that was only after I started timing after we had been waiting what seemed like a long time. The people who had been ahead of us in line had ridden and gotten off way before we even boarded. We had no choice because our DD uses a wheelchair and needs the wheelchair accessible boat.
The people I felt sorry for were the people who were using GACs with ambulatory kids. They ended up trapped in the line with us and could not leave, even though they didn't need a special boat.
The same thing has happened to us many times on the Safari and Spaceship Earth.