Wat Phra Kaew This large temple is in a separate compound between the town and the historic park. However, one ticket serves for both attractions. This site needs to be walked as it is smaller and has no roads.
One unique feature of the temple is the cluster of 3 Buddha images; two seated and one reclining.
These great old trees are worth some appreciation as well.
Most people will be able to see the park, Wat Phra Kaew and the Museum in one day since travel is not a significant factor.