This is a very easy and classic view to get to within Yosemite. Simply take the Hwy 41 turnoff towards Bridal Vail Falls and Glacier Point. Just up the road you'll see a tunnel and a parking lot on either side of it's entrance.
I made my annual spring trip to Yosemite in search of blooming Dogwoods and instead was greeted by a rain storm. Towards the end of the day I made my way to one of my favorite views of the valley in the hopes that the clouds would break. My prayers were answered in a very colorful and dramatic way as the setting sun put on a very impressive but short display of color.
Tunnel view is one of the classic Yosemite sights but one that as a photographer you have to have for yourself.