Experienced this last week, and we split up, with me getting FPs and the rest of my family heading back to the ride. Virtual Insanity has covered this well. If you want to get FPs, you want to use the main entrance, and get there early. The FP line will be roped off towards the left of the Carthay Circle, towards the Hollywood section. You must get in the FP line there - you will not be allowed to enter it if you stay to the right at rope drop.
Those who are not getting FPs can use the "wide right" strategy to get into the stand-by line a little quicker.
We employed a hybrid strategy that worked well. I took the tickets and went to the FP line, while everybody else waited in the "regular" area before rope drop. Upon rope drop, they headed for RSR, but not at top speed, for both practical (a stroller, an 8-year-old, a 10-year-old, and just one adult) and strategic reasons. It took me about 15 minutes to get FPs, after which I headed back to RSR and entered the single rider line. We all got to the loading platform at roughly the same time. Although we didn't get in the same car, we were only a couple minutes apart.
Another tip. I assume that I experienced something normal when my RSR FPs said that I did not have to wait until the FP window or two hours had elapsed to get another set of FPs. I noticed this on my way back to RSR to hit the single rider line, and quickly (but without running
) detoured through Bug's Land to grab ToT fastpasses and then back through the back exit of Bug's Land into Carsland to hit the single riders line. My ToT FPs were so early that we rode just after getting off RSR on that first ride.
For what it's worth, we used a similar splitting up strategy later in the day when it was time to use our RSR FPs. At the beginning of the FP window, I entered the FP line with the 3 year old (just tall enough!) while the older kids and my wife hit the single rider line. Again, we all rode at about the same time. After getting off the ride, we were still in our FP window, so this time my wife took the 3 year old in the FP line and the rest of us went single rider. Again, we all rode at about the same time, although not in the same car.