Consider biking

Few people do it but visiting the Yosemite Valley by bike is very pleasant. You can bring your own bike (this is what I do) if you have a bike carrier for your car. But you can also rent bikes in the park.

More information on the bike trails (including a trail map) and rental information is available here: http://www.yosemitepark.com/Activities_Biking_BikeRulesandTrailMap.aspx

I also found a nice video overview of biking in Yosemite: http://www.youtube.com/watch?v=JHauqjTHw4Y

in reference to: Yosemite National Park - Plan Your Visit (U.S. National Park Service) (view on Google Sidewiki)