We just ate at AG this morning - getting there from GCH is actually the best (and fastest) way to get there. Once you enter just go to your right and stick to the road. When you reach the white rope just let the CM there know that you have a PS for AG and they'll let you pass and direct you where to go.
From the main entrance you'll need to take the route through Condor Flats (which is towards the GCH entrance).
Have a great time! Our breakfast this morning was amazing!!!!