I visited Tenryuji (Temple of the Heavenly Dragon) several times during my six-month deployment to Japan. I found it to be one of the most beautiful temple complexes for the beauty of its gardens, the nearby bamboo forest, and its Zen restaurant Shigetsu. It was definitely my favorite temple in Arashiyama, and would be my first stop if it is your first time to the area. It's about 40 minutes by train from the central Kyoto train station; there is plenty of signage from the train station to the temple, unlike some of the smaller temples in Arashiyama. Be sure to give yourself enough time to leisurely explore the gardens, which are some of the best in Kyoto.
There is a small gift shop that sells several different photo books of Tenryuji's gardens and temple grounds in various seasons; this makes a great souvenir and wasn't overly expensive (I believe the book I selected was about 1200 yen and included English captions).
If you're interested in eating at the Zen (vegan) restaurant Shigetsu, you have to make a reservation in advance, but it is well worth it; there is a separate listing for Shigetsu on TripAdvisor.