I recommend taking a telescope to Glacier Point and staying up late and looking for our neighbors Mars, Venus, Jupiter, and Saturn. With a lesser telescope, you can actually see the climbers on halfdome. Tuolome Meadows is a great place to have a picnic, sketch, practice thai chi, or simply lay down and relax. I will always cherish driving up at 3am to be there for the first sunrise of 2000.
Quick Tips:
Take a date, it can be quite romantic, no matter where you are in the park!Best Way To Get Around:
Around the park I recommed walking and biking. Every able-bodied person should experience Yosemite in person, not from the car.