You have to get there very early in the morning in order to see the forest elephants. There may be monkeys hanging around, LOL, but the forest/jungle itself is fascinating as is the canopy walk.
Also, strongly recommend visiting the castles along the coast. A lot of history there, mostly sad. Unfortunately, you probably wouldn't have time to do both, Kakum and/or the Castle.
Try the Star Beer if you can. It is very good.