With only parts of two days to spend in the park, I wouldn’t suggest entering on Jubilee Pass and north on Badwater Road unless you have some special reason for wanting to. It’s very scenic and I would certainly suggest it if you had more time. However, it adds almost an hour, and the southern 50 miles of Badwater Road are more about long-range vistas of the mountains and valley than specific natural wonders. The only real specific landmark on this stretch is Ashford Mill, the ruins of an ore smelter for mines in the nearby mountains. There’s little to see, the mines are not accessible except by a long and strenuous hike, and IMO it is not worth adding that much time. The main natural wonders that you want to see are in the northern 17 miles of Badwater Road.
If you take this route in and then 190 east to Dante’s View, the best way to Beatty is to go back on 190 west and continue on it to Beatty Cutoff Road. A route you may find on some map programs is east on 190 to Death Valley Junction, CA 127 and NV 373 north, but this is 5-6 miles longer and far less interesting.
From Las Vegas to Pahrump, Shoshone, and Jubilee Pass, including the trip to Dante’s View and ending in Beatty, will be close to 300 miles.
It’s shorter and just as scenic to go from Pahrump to Death Valley Junction, enter the park on 190 and go to Dante’s View first, then Zabriskie Point. After Zabriskie Point, you come to the 190/Badwater Road junction, and you could go down Badwater Road and see Devil’s Golf Course, Badwater, Natural Bridge, Artist’s Drive, and Golden Canyon. If you do it in that order, you’ll make a loop trip south and back north with a minimum of crossing over the road. It’s 17 miles from the 190 junction to Badwater.
Rather than doing Badwater Road first, you might make the 1-mile detour to Furnace Creek where the Visitor Center is, so you can see the park movie and exhibits and get your official map after paying the entrance fee. A little time there will give you a better idea of what you’re seeing. You could have lunch at that time or decide to wait until after the Badwater sights.
If you do this rather than the Jubilee route, the distance from Las Vegas to Beatty, including Dante's View and Badwater Road, will be closer to 200 miles.
I don’t know why you are staying in Beatty, but if you can get a vacancy at one of the park resorts and it fits into your budget, that is a far better choice. It will mean less time driving back and forth and a more authentic experience. Beatty is a nice little town, which you already know if you've read my User's Guide to Beatty on the Neavda forum, but it’s still a town. Staying in Death Valley will put you in natural surroundings with the magnificent landscapes all around, a chance to see the natural vegetation and probably some wildlife, and dark night skies. Furnace Creek and Stovepipe Wells Village are well situated for your itinerary and the things you want to do.
The ride from Beatty to Scotty’s Castle on 95 and 267 is questionable. North Highway (aka Castle Road) within the park is closed east of the Castle because of flashflood damage. This happened in the summer and there is no estimate on when it might be fixed. From the Castle down to 190, the North Highway is open. So from Beatty, you’d have to take NV Hwy 374 (with an optional stop at Rhyolite ghost town), then Mud Canyon Road and Castle Road north.
The Castle tour lasts about an hour, and there are grounds to walk around, a visitor center with exhibits, Scotty’s grave, the 1930s boneyard with surplus building materials and dead equipment, and other features. Since you are going to Ubehebe regardless, it’s worthwhile to see the Castle. The Castle and the park Visitor Center are open every day of the year, including Christmas Day. Castle tours are given daily, but on Christmas there are usually no special programs at the Furnace Creek Visitor Center other than the regular park movie. The Crater is a unique and interesting part of Death Valley, and the time you spend there will depend on whether you want to hike down into the crater or around the rim. Just to go there and see it will not take lots of time.
Devil’s Cornfield and the Sand Dunes are also open as to time commitment. Most people want to spend some time walking around in the dunes. You can pull over anywhere there is space to get clear of the traffic lane, but the closest place to walk to them is a marked asphalt parking area off Hwy 190, which also has an outhouse. Mosaic Canyon is a hike, but it doesn’t have to be long and strenuous. You can see some of the beautiful polished white walls and broken rock surfaces with a walk of 20-30 minutes. This will be very near Stovepipe Wells resort; you can stop there for a bite or wait until Panamint Springs, another 30 miles west and next to the Darwin Springs road.
As for access in a regular car, the Devil’s Golf Course, Natural Bridge, and Mosaic Canyon roads are graded gravel that’s maintained regularly. They are fine for any vehicle driven carefully. The road to Darwin Falls from near Panamint Springs often requires 4wd and/or high clearance. It can be rough enough that I would seldom suggest a regular car, especially in winter when there may have been rain. Also, by the time you do the other things, it will be afternoon when you get to Darwin Springs. It is a riparian environment with lots of vegetation and high walls, so there isn’t full sunlight even in much of the afternoon, and you’ll have limited time to get there and explore before it will be too dark to see anything.
Finally, after a full day of exploring Death Valley, it’s a long haul to Simi Valley. From Beatty to the Castle and the Crater, then the places along 190, if you go out to 395, the day’s mileage will be close to 400. Considering all the sightseeing and hiking, this can be a fatiguing day. West of Panamint Springs, Hwy 190 becomes narrow and twisty with steep drops, where there is no room for error or drowsiness. If you must do this at night, I would suggest not taking 395, but turning south at Panamint Valley Road (the major junction just east of Panamint Springs) and going through Trona and Ridgecrest. This also cuts off a few miles.
If possible, I wouldn’t suggest trying to make Simi Valley the same night. Can you add one more night and maybe stay at Stovepipe Wells or Panamint Springs? That will give you a desert experience that you’ll have missed if you spent the first night at Beatty, and you’ll be fresh for the morning’s drive. There are also lodgings at Ridgecrest, Mojave, and Lancaster.
Edited: 11:29 pm, October 21, 2012