If you don't care about the details, here's the latest road/snow conditions in the area: Monitor Pass is open, Ebbets Pass should be opening soon, The road to Virginia Lakes is open all the way, Tioga Pass is open all the way to the pass (but only from the east side!), and some people I talked to said it may even open before Memorial Day if the warm, dry weather continues. The skiing/snowshoeing conditions are great - firm, well-consolidated snow. Most of the ridges are already snow-free, and there are at most only a few feet in other areas, so summer will come quite early this year.
For Castle Peak, I started at the snow-park off I-80. Not wanting to wait to buy a parking permit, I drove a few feet up the road/winter trail that is under/across the highway from the main parking area. With the snow already partially thawed in spots here (~7200 feet), many other people were also avoiding paying for the passes and parking here. The route to the peak is very straightforward: follow the road and then trail north to the ridge of castle peak, and that ridge leads to the summit. No snowshoes required in the firm morning snow, and the crampons/ice axe didn't leave the pack either. There are a few summits, all short class 2/3 scrambles. The top half of the peak is largely snow free already, and there is no snow on any of the summit rocks.
Awesome views of the peaks to the south including Tinker Knob. This is a popular short hike: I met over 20 people heading up as I descended. Almost back to the car, I was walking along when I felt sharp paws on my back and found myself face down in the snow before having a chance to even look around. Aggressive bear? No, it was someone's friendly 300 pound St. Bernard saying hi!
Round trip time for this peak: 3 hours - it would probably take 4-5 if the snow was thick and the steep climb along the final part of the ridge were snow-covered.
Saturday afternoon I ended up at Carson Pass and decided to do Round Top. The sign at the parking area says that snow-park permits are required until May 30, although many cars were parked along the partially snow-free spur roads near the pass.
Dozens of skiers/snowshoers were enjoying this beautiful area, and I followed an excellent path south to Winnemucca Lake along gentle slopes with easy route-finding. Many tents were set up around the lake, and people could be seen on just about every slope around. There was even a group of skiers descending the Round Top couloir! As for me, I took the easiest slope southwest to the saddle on the west side of Round Top (ice axe/crampons were helpful) and then followed the completely snow-free ridge to the top.
Great panoramas in all directions. Red Lake Peak is almost completely snow-free, and many other neighboring peaks had continuous snow only in the couloirs on the steep slopes above treeline.
Round Trip time: 4.5 hours at a leisurely pace - great snow conditions (where there was still snow!)
I drove to Bridgeport via Monitor Pass (completely snow-free) and went up to Virginia Lakes for the night after learning that the road had been plowed a few weeks ago for spring ice fishing. Several other groups of hikers were also car-camping there. The fishermen arrived en masse just after sunset and I set out for Excelsior Peak. Route finding was very straightforward: i headed to the area between Dunderberg Peak and Black Mountain and after reaching the lake a few minutes northwest of the lake near the trailhead, I followed the approximate course of the summer trail to the pass, crossing several of the frozen lakes en route. The slopes are not steep, and there are very few trees that obstruct the view to the pass. From there, Excelsior Peak comes into view. It looks deceptively far away but is an easy ascent. I climbed the hill in the foreground of the summit ridge, which leads to the summit ridge of excelsior after a short ~100-foot drop in elevation and then a short climb to the bump that is slightly north of Excelsior. The route was largely snow-free after gaining the hill in the foreground of Excelsior.
Only one other party has been to the top so far this year. The peak has a tremendous view of northern Yosemite, Mt. Conness, Mt. Dana, Mt. Lyell, Ritter, etc. There are no higher peaks further to the north (until Shasta), although that can probably be said about many of the major sierra peaks north of the palisades...
Round-trip time was 5 1/2 hours - this is a beautiful and not too strenuous spring climb if the Virginia Lakes road is open. The slopes of Dunderberg Peak that rise from Virginia Lakes are almost completely snow-free already, though I saw some skiers in the steep couloirs on the way down (the same ones crazy/good enough to do Round Top couloir the previous day?)
Ice fishing seems to be very good at the Virginia Lakes: there were dozens of people on the lake near the parking area, and the people I said hi to had caught 15-20 large brook and rainbow trout. A much better lunch than ramen...