I'm a long-time volunteer at SnF and have a bit of knowledge on this. The following is for car transportation only.
The inbound driving line to parking is normally not all that lengthy time-wise, with the exception of Friday and Saturday morning. Peak inbound traffic time is normally about 8:30 am. Outside of Fri and Sat, you should expect to wait no longer than 15 min to get into the parking lot. IF there have been recent heavy rains, the parking areas will be limited and driving times increase.
The walk from Parking to the front gate is normally 5-8 minutes. Once inside, you're close (within an 8 minute walk) to almost every major attraction.
Car departures can be lengthy, especially after the end of the airshow on Fri, Sat and Sun. The good news is YES, there are plenty of attractions that remain open for you to pass the time after the show is over. While the hangars will be closed (no commercial vendors hawking their cool wares), there are a couple of restaurants and bars open, along with food trucks. And you can always enjoy the major aircraft parking areas offering eye-candy galore.
RV-6A (which I sadly admit I did not build)