My dad and I had planned to go to Yosemite, expressly for the purpose of climbing Half Dome, on Memorial Day. Unfortunately, I was busy preparing for finals, so we didn't go. Accordingly, the last weekend before the start of summer quarter, we loaded up the car, and headed out.
I don't think summer is the best time to visit Yosemite valley. However, we had the advantage that with the snow gone, both Glacier Point and Half Dome were climbable. So we did hikes to both, and have some pretty amazing views to show for it. I even lost my camera's lens cap coming down the cables on Half Dome while trying to take a picture. A fair trade though, I'd say!