If I were you guys and had the luxury to do so, and wasn't hauling a bunch of stuff and a trailer to the Bash, here is what I would do:
First, - Take the pressure off about being on time. Meet somewhere for a nice breakfast for an hour or more; gather up, have some fun just getting together. Let others flow in so you can achieve a larger caravan, depart by 11 or so.
Second - Pick a nice scenic route driving up, enjoy, take your time getting there. Smell the roses on the way up.
Third - Not be in a hurry, arrive whenever but not much later than 6pm as things start to buzz around 6pm there in the Corral and the Track Meeting is at 8pm.
Fourth - Take some pictures along the way. Stop a few times just for the heck of it. Make a scene somewhere. Last year, some of the best photos were taken by people getting to WSCB.
Remember, Thursday is casual arrivals and nothing is scheduled. Have fun, good luck, and we'll see you guys there!