Shelf preference really depends on what you'll be cooking-- the one downside to the full upper grate is that it's somewhat difficult to reach the back of the grill on the bottom. So if you're doing mostly low and slow things like pork butts, where you won't have to be moving them much at all, it might be a great fit and give you the most square inches. However, if you're doing things that you're going to be flipping, turning, etc. the three quarter allows for a little more room to reach the back of the grill on the main cooking grates, while still giving you plenty of extra surface.
Definitely get either a 3/4 or full upper track, and I love the griddle. With those two options you will greatly increase the versatility.