We were planning on going in on Thursday morning and avoiding the Valley as much as possible until the end of our stay (after the holiday weekend). Unfortunately, there was an unexpected death in my family and we were in Connecticut for a funeral until Saturday afternoon. That meant we got into the park on Sunday afternoon. I considered going in at either Arch Rock or the South entrance but, from force of habit as much as anything else, came in 120 (we were coming from SFO). It was clear sailing until about a mile outside the entrance station. We sat in line for about 45 minutes there...not bad compared to some stories I've heard (*) but, given my normal ability to time my entrances, it was by far the longest we've ever sat in line. From the other side of the gate down to the BOF/41 intersection by the river, all was smooth again but very quickly after turning onto 41, we inched along and it took me at least another hour to get to the turnoff for Wawona (we were staying in Yosemite West). Heading south on the road was fine once we got past the cars trying to turn into the BVF parking area but coming north, cars into the Valley, it was bumper-to-bumper to a little south of Turtleback Dome (and based on what I saw on the Southside drive when we turned off, it was probably bumper-to-bumper throughout the Valley). All-in-all it was 7 hours from SFO to Yose West...a trip that typically takes us about half that time.
We were able to avoid pretty much all significant traffic for the rest of the trip (although my wife tried to go into the Valley on Tuesday afternoon while I was out for a long hike (she's recovering from a broken ankle so could only join me for portions of my hikes) and she said traffic and parking around the Village were pretty awful).
I'll post some TR's after I have a chance to get settled in back home (we just got back late last night) but the Sunday experience was ample evidence to confirm that one should never try to come into the Park on a holiday weekend.
(*) A ranger we spoke with on our way out of the Park said that the wait at the 120 gate earlier on Sunday (we didn't arrive until about 2:30 pm) was averaging 4 hours!