During my time in Yosemite I stayed at the Yosemite Lodge. The first night I was in one of the more expensive rooms and the following two nights in a cheaper room. They both seemed fine to me. Reservations typically need to be made at least a year in advance.

The first thing I noticed about Yosemite is that it is very crowded. Tons of cars. The second thing I noticed is that there are a lot of foreign tourists. Especially from Germany and France (but I also heard quite a few Italians, English, etc...). Granted we went in August and August is a big vacation month pretty much everywhere. So if you go some other time there may be fewer people. A surprise to me is that the park is open year round. One thing I would highly recommend is that you use the shuttles when you are on the valley floor. So much better than driving.

We didn't have a great deal of time and so had little time for lengthy hikes. We instead concentrated on seeing as much as possible in the time we had. We went to Glacier Point, Bridalveil Falls, and pretty much all of the other major sites. This takes a good day and a half and you'll get plenty of small, easy hikes in. If you have more time there are lots of longer, more difficult hikes.