We visited Uluwatu Temple while staying in Seminyak which was about a 45 minute drive. I would recommend going first thing in the morning to avoid crowds, however I did hear that the sunset is beautiful from this spot and that you can see a traditional dance in the late afternoon so it would depend on your preference.
Monkeys are all over this temple. Watch your phones, glasses and hats as we saw somebody lose sunglasses while there. They are looking for food, so just keep all of that away and watch around you and you’ll be fine. This is quite a large temple which has cliffside views of the ocean. It’s definitely a cool spot to visit. Make sure your knees and shoulders are covered. If your knees are not covered, there are sarongs available to wear onsite.