Hi, I'm going to California in June and have a rough itinerary: SF-LA-Joshua Tree-Las Vegas-Yosemite-SF. I have 10 days (13-23june) for the "Joshua Tree-LV-Yosemite"-leg and would like to avoid booking any accomodation on the way so I can change my schedule easily. (I'm hoping Tioga Pass will be open late June!!)
People seem to be advising everyone to book a year in advance and no later than now. Am I crazy not to book accommodation in/around Yosemite before I arrive? My budget is $100-150 (max $200) pr night...

Depends on how far you are willing to drive when you go to Yosemite. It's probably alread too late to stay in the valley so you're looking at a 45+ minute drive. You should have a list of accomodations ready so that you can reserve something as soon as you've locked down your itinery. There are NOT a large number of affordable accomodations near to Yosemite. I'm only familiar with the North Entrance. In order of closness to the Valley Floor. Buck Meadows (45 min), Groveland (1 hr), Jamestown (1.25 hrs.), Sonora (1.5 hrs.), Oakdale (2 hrs.) There's a place that rents Yurts on Hwy. 120, Can't remember the name. It's a RV park on the River with these Yurts for rent.

Good luck.

I'd make reservations. Otherwise you are likely to spend quite a bit of your time hunting for a place to sleep.

If you are driving from Las Vegas to SF via Yosemite, you must be counting on Tioga Pass being open. While it usually opens in May, that is not always the case. Last year it did not open until June 24. And in 1998, although the "official" opening date was July 1, we were not allowed to drive over the pass until July 4. Given that this is a "late snow" year (there is snow on the Valley floor now), it is possible that it will not be open in time for you. You might consider plans for an alternate route as a backup plan. As for lodging in and around Yosemite, you can check on what is already full here:
http://www.yosemitepark.com/
There are still some rooms or cabins available mid-week at Wawona and Curry Village (rustic tent cabins), as well as outside the park.

Regardless which route you take, if you arrive without reservations, you could spend a long time driving around looking. Or you might get lucky. I hope it works out for you.

Have you thought about doing your trip in reverse. Do Yosemite first so you can better guess what day you need to be there...or course then you run the risk of Tioga pass not being open yet.

It's probably to late to make reservations in the park anyways but a little secret I've learned is to call 10 days before you need to stay in the park and see if you can get in on a cancellation.

Utahtea

Ditto what others said. The Valley will likely be sold out and you'll spend your vacation time driving to towns outside the park looking for accomodation, and quite possibly not finding any for a long way. You also don't have a very good chance of finding lodging within your budget if you don't reserve.

Don’t want to “rain” on your carefree style so I’ll provide a couple of ideas:

This year we are have crazy amounts of snow. Last year with a bit less snow Tioga Pass opened June 23rd. It is becoming more and more likely that it will not be open during your dates. If that is the case here is one way to travel through Yosemite without prior arrangements:

Vegas to Yosemite will be a long driving day. Come up through the south entrance on 41 and stay overnight in Oakhurst. You could find available lodging there. If there is still enough day left, go into the park and explore the Mariposa Grove and, if you like, check out the Wawona area. Your entrance fee is good for a week so keep your receipt. Always contact the Yosemite Falls Lodge to check for cancellations. Also check Yosemite View Lodge, Cedar Lodge and other El Portal lodging to see what, if anything is available. If Tioga Pass is not open there may be more than the usual number of cancellation from travelers who counted on the pass being available. If you find nothing you may have to go back to Oakhurst or find lodging further out on 140 or up on 120 like Groveland.

If Tioga Pass is open then drive from Vegas and stop in Mammoth or Lee Vining for the night. Make your way into the park the next day stopping at Olmsted Point and Tenaya Lake before going into the valley. For lodging use the ideas discussed above. You should not plan to go back to Lee Vining though if you don’t find anything in the valley or El Portal. Instead plan to go to Oakhurst. At least you’ve spent the day in the valley and the next day you can check out places like Mariposa Grove, Wawona and on to Glacier Point.

Good luck!

Thanks for quick replies and very helpful advice!!