We stayed in Yosemite just a month or so ago. We came in on 140 and went out on 120. We stayed at Crane Flat (kind of at the corner of 120 and 140) and loved it. Here is what we learned.
Stay in the park. The drive to and from the park from anywhere outside is a bit of a hike. It is also very expensive to stay outside the park. We did not plan very well for our trip (typical for us) and when we got quotes from RV parks outside the park it was 70-100$ a night for full hookups. When we stayed in the park it was 50% off using our National Park Pass and it was 10$ a night. It is much easier driving down to the valley floor from inside the park. If you stay on the valley floor it will be HOT. Like 90-100 degrees eveyday. Dry but hot. We stayed in Crane Flat (@6000ft) and it was in the 70s during the day and 50s at night.
There are very limited spots for 40' buses in the park. Crane flat only has about 2 or 3 spots that will fit 40' buses. Be prepared for the most challenging experience of your life if you have a 40' bus and want to park in Crane Flat. I had about 30 people standing and watching me try to pull up the hill to the first spot we stayed at. I apologized to them all (for the smoke screen I layed down) after I parked the bus but they were all amazed that the bus made it up the hill and around the trees. It doesn't hurt to unhook and go eyeball your site before you pull the bus in. We had to pull it in going the wrong way on the one way circle as it was the only way it would fit.
When you book - Best to book online. they have all the site sizes and pictures on the website(google maps helped as well). The national park website is well done. If you are not on the valley floor then know that none of the sites are level, Its a spot on the mountain in the hill. No hookups. We found out that the Handicapped accessible sites can be booked for people that are not handicapped if there are no other sites that will fit your vehicle. In other words if you are trying to book for the summer now there aint gonna be much for a 40' vehicle and if you can only take an ADA site its okay. We stitched 6 days together at 2 different camp sites in Crane Flat to make it work. There are only dump stations on the valley floor. Make sure you can go for the length of time you stay there without hookups. Driving down the the valley floor would have not been fun for us. then trying to get the bus into the dump station and fill up would just be a bummer with all the traffic and craziness that is down there in the summer. There are no showers at Crane flat (and many other places that are not on the floor) You can drive into the valley and take showers at the campgrounds on the valley floor.
Driving into the park on 140 was fine. it was 106 degrees in Merced when we went and the engine was HOT. We had to pull over a couple times, finally dumped the toad and had the engine door open and that helped. Keep in mind our toad is 8000lbs and we have a 6v92. Watch your temps pulling those hills. They are tough. There are two spots...one coming in from 140 and one going out on 120 where you need to put it in 1st going down hill and ride your jakes all the way. Its very steep and winding road. Like RJ said....go slow and stop for oncoming traffic. Pull over to let traffic by when you can. At 25 mph I thought we were going a bit fast. There is a single lane bridge like RJ said that is managed by a traffic light going in on 140. Not a big deal...if you are over 13'6" check online to make sure you will fit...I think the clearance was low..we are 12'6". It is a beautiful drive. In and out.
Once you are in the park dont be afraid to stop at the first place you can park and take the park buses all around. You dont need to drive at all on the valley floor. Buses will get you everywhere you need to be. Word on the street is they are gong to eventually make it like zion where you need to park in a lot and only take the bus through the park.
Mist trail was our favorite. it is a good hike and 700 steps up to the top at the end. It is strenuous but take your time and bring food and water and enjoy the hike. Vernal falls is at the top and is amazing. Lots of other places to see and things to do which are all amazing. Dont be afraid to get off the beaten path.
Have fun. Here is our blog post about it -
http://www.herdofturtles.org/2014/06/22/yosemite/-Sean
