Several times, I rode Encinal to Decker to Mulholland (in both directions), but have never done The Snake down to The Rock Store and to Lake Vista back to Mulholland and right on Las Virgenes and ride through the tunnel to Pepperdine? We did 4,890' of climbing Saturday and 70.1 miles in just under five hours. But I have never cycled The Snake or through the Las Virgenes tunnel. What are thoughts & experience on this route?

First, it's Mulholland Highway, Mulholland Drive is the road above Sherman Oaks and Studio City which turns to dirt above Encino and then has a little more West of Canoga.
By "The Snake" I guess you mean the part of Mulholland Hwy from Kanan down to the Rock Store? It's a fun descent but can be dangerous near the bottom. Some of the turns are very tight and some spots will be wet or have leaves on the road. Use you head and you'll be fine.
I don't like the traffic on Las Virgines and prefer to descend Encinal or Latigo or even Topanga. LV is a great road, just too much traffic at times. If you go there at the right time it should be fine.

I used to hang out at the rock store and race my motorcycle up there. Now that I ride non motorized bikes I wouldnt ride there on weekends. Too many yahoos racing and crashing.

Agreed that LV is trafficy. However I do it every year as part of the Mulholland Challenge. But then I'm doing it at 7am on a Saturday. But it's something different. BTW, south of Mulholland it becomes Malibu Cyn Rd. Rock Store Hill is a fun descent but, yeah, a lot of yahoos there who are hell-bent on suicical tendencies. If you can sweat-out ascending Cotharin, Deer Creek Rd is a fun terrifying descent.

I'm probably on Rock Store about 3 or 4 times a month. I try not to ride it after 10:30 in the morning as the traffic picks up. As mentioned, on the downhill, the shady areas can be wet so caution is advised. In the hot weather, I really like it in the morning.

As to Las Virgenes/Malibu Canyon out to the beach....agree with John...I wouldn't ride it myself. It's narrow and full of cars most times of the day. I rarely see roadies on there...once in a great while or during the Mulholland Challenge but that's it.

Better yet, turn onto Piuma Rd (traffic light where LV becomes Malibu Cyn); enjoy a 4.5 mile climb to the 2200 Ft peak and a breath-taking panoramic view from the mountains to Catalina. Descend to Los Flores and another 3-4 miles to PCH (you'll be 3 miles south of pepperdine). Smooth road is Piuma and traffic is very light.