Mount Batur is an active volcano up in the Balinese hills. There are tours aplenty to take you to see 'active volcano with lava running down its peak'. This vision is not a dramatic as you would imagine and I couldn't see any lava spilling over the sides from where I was standing but it is still a pretty impressive view. You can also go on a hikes up the volcano early in the morning and then perch yourself on the summit and watch the sunrise. Who needs lava really.
On the guided tour of the Monkey Forest you don't really go into the forest, it is more like Monkey stoney paved area but still the monkeys are there all the same. The place is littered with monkeys and is great for some photo opportunities but the novelty wears off pretty quickly. In addition, whether you want one or not you are given a 'guide' to show you around the Monkey Forest. They don't do a lot other than point at monkeys but unfortunately it's compulsory. To pay for the guides services you then have to buy something from their shop which is of course ridiculously over priced. I came away with a wooden Buddha statue which cost about £10!
Tanah Lot at sunset
Tanah Lot is a great photo opportunity location. An unusual rock formation topped with a scared temple sits on the edge of the sea. Visit in the evening to see it at it's best while the sun is setting.
The whole island is covered in rice paddies but the really special ones are in the hills where paddies have been layered up into terraces creating a beautiful ripple of green. Most tours will include a visit to one of these on the trip. One of the most well-known is Tegallalang Rice Terraces just outside of Ubud.
Temple of Mengwi
In my opinion one of the better temple complexes in Bali. It's pleasant and easy to walk round complete with the iconic Balinese layered black towers. You can see this style across the island but this temple is easy to get to and you can walk around at your own pace without to much bother from vendors.
Goa Gajah (Elephant temple)
This temples, like most others, lays within a larger complex with winding hilly paths and deep green ponds scattered around. Once you leave the initial chaos in the carpark, it is a lovely place to stroll around. The temple itself is more like a cave carved into the rock. Only shallow, once in you will see the usual offerings and a statue or two with incense smoking away.