- Get someone to drop you off and pick you up.
- Drop your car off at the finish and have someone shuttle you to the start. I suppose you could do the reverse too.
- Take mass transit to the start and back from the end.
- Drive to the start and take mass transit back.
The first two options require having friends, so I was left with the second two. I originally intended to take mass transit both ways, but due to an airline scheduling screwup (details here), I didn't have time to take transit and had to drive out to Yosemite. I figured that maybe I could bum a ride back from Whitney from some other hikers and in the worst case, I could take transit back.
I really do mean the worst case here, since the transit situation is pretty grim. The nearest trailhead to Whitney is at Whitney Portal, which is basically just a parking lot, campground, and store in the middle of nowhere. The nearest town to Whitney Portal is Lone Pine, 11 miles away. The official story about getting from Lone Pine to Yosemite Valley is that you take CREST from Lone Pine to Mammoth (leaves Mon, Tue, Thur, Fri at 6:15 AM, arrives Mammoth at 8:20 AM). You then take YARTS from Mammoth to Yosemite Valley (leaves 7:00 AM, arrives 10:55 AM). Yes, you're reading that right: CREST arrives in Mammoth 80 minutes after YARTS leaves for Yosemite. Now, I've never personally been to Mammoth and I hear it's kind of nice, but after a couple of weeks on the trail, I suspect most people are ready to get home—I know I was—so this doesn't seem like a real attractive prospect, and I went looking for alternatives. First, I'll tell you what I did and then I'll tell you what I probably should have done.
You may have noticed that I've left something out of our little trip. When you get off the trail you're still stuck at Whitney Portal and you need to get to Lone Pine. There are shuttle services, but really this part is pretty simple; the road to Whitney Portal (cleverly named Whitney Portal Road) from 395 runs right through the center of Lone Pine, so more or less anyone leaving Portal is going to go to Lone Pine. A decent fraction of them have room in their cars and are happy to pick up backpackers, so hitch-hiking this section is easy. That said, I was hoping that I could get a ride to Yosemite or Mammoth from someone who was executing the aforementioned option 2. I hadn't met anyone who fit the bill, but I figured some people might come off the trail so I made a "Yosemite/Mammoth" sign and stood by the exit to Portal for an hour or so. After about 10 people had stopped and offered to take me to Lone Pine, I got the idea, put down my sign and stuck out my thumb and got a ride within 5 minutes.
This got me as far as the Whitney Portal Hostel, but again I was hoping to avoid two overnights (one in Lone Pine and one in Mammoth). One of the other people staying at the hostel suggested I try hitchhiking [remember, 395 is the main strip in Lone Pine]. After a few minutes with my sign, I ran into a woman pushing her kid in a stroller who said that her family was driving to Tuolumne the next morning and they could probably take me. After some negotiation with her and her husband, we were on. I met them at their hotel the next morning and they dropped me off at the Tuolumne store around 11 AM. Now remember, I really wanted to be in Yosemite Valley, which isn't exactly an easy walk from Tuolumne. Luckily, there is a bus that leaves from the store at 2:15. This isn't a a terrible option but it still leaves me sitting around for three hours, so I figured why not try to hitch it the rest of the way? Five minutes with a marker and a cardboard box and I had a new sign and was standing out on the road. A few minutes later, another hiker who had come off JMT the same day as I had walked over. She helped me improve my sign (with a better pen) and we chatted as people drove by without picking me up. After 45 minutes or so a van full of Italian tourists (I hear Europeans are better about this than Americans) came by and picked us both up, taking us to one of the Valley parking lots by around 2 PM. From there, you can take a quick shuttle to the trailhead parking and your car.
Anyway, what I learned from the other hiker was this: don't take the bus to Mammoth. Instead, take the same bus all the way to Lee Vining (a town right near Tioga Pass and the entrance to Yosemite). Because Lee Vining is more or less at the intersection of 395 and 120, it's easy to hitch a ride from people driving into Yosemite from the East Side; she said that she spent about 5 minutes waiting before she had a ride into Tuolomne. Even if you can't hitch a ride, the worst case scenario is that you take the same YARTS bus the next morning into Yosemite Valley, so aside from having to spend the night in exciting Lee Vining instead of Mammoth, you're no worse off. Of course, this advice only makes sense if you don't mind hitch-hiking; I usually wouldn't be willing to, but it's common enough near Yosemite that you don't have to feel too awkward and I generally feel like I can take care of myelf. Your mileage may of course vary.
UPDATE: The CREST bus arrives in Mammoth after, not before the YARTS bus leaves. Thanks to Eu-Jin Goh for pointing this out.