Hi, just got back from Cameron last Sunday (23/11), your questions were actually quite subjective,but the answers given by Vkumar33 are pretty good guidelines.
It depends on your interest, are u going with family, children? old folks?, etc.
I believed it would have helped you more if you could be more precise in your questions.
Me and my family(mum(70's), brother,sis-in-law, son(10), daughter(13), wife) spent about an hour just at the Tea House(Sg Palas)enjoying a cuppa and taking in the view and the fresh air! Relaxing and refreshing!!
Factory visit about 20 minutes.
Cactus farm, we skipped.
Butterfly Garden - we spent about 45 minutes, including taking lots of photos of butterflies, flowers, scorpions, insects, etc.
Spent another about 20 minutes at the souvenier shops at the Butterfly attractions. Just for your info, there is a Butterfly Farm and there is a Butterfly Garden, and they are next to each other.
Like Vkumar33 said, may be worth a visit to the strawberry farm and do some strawberries picking, especially if you have children. Was an experience for my kids and even my mum. We spent more than an hour there including trying out their strawberry juice drink(strongly recommended), only RM3!!
Unless you are time-tied, if not I would suggest like what we did, we just spend more time at the places that we were enjoying ourselves. Holiday is about relaxing and enjoying ourselves!
We went to the Time Tunnel Gallery, and were pleasantly surprised that we enjoyed the travel back in time when going thru' the items of yester years that were displayed.
We also visited the pasar pagi/tani and the vegetable market at KEA Farm area, we picked up local produce that are unique and special.
We visited 'Ye Old Smoke House' for its ambience and tried its tea with scone (Warning: it cost a bomb - well as far as we were concerned). Nice photo spots there.
Hope the info was of help to you.
And please drive carefully, i.e. if you are driving, there were a lot of reckless drivers on our drive up and down Cameron Highlands via Simpang Pulai. They were driving recklessy, tailgating, and overtaking at double lines, at sharp corners, cars and lorries all doing the same, even when it was raining.
My bother's car was hit by a car that was trying to overtake at a corner and upon seeing a oncoming car tried to get back into the lane and hit my brother's car in the process. Luckily my brother was driving at about 50 - 60 km/h, and there were no other oncoming cars, as his car swerved, upon impact, on to the opposite lane towards the concrete barrier, but he managed to swerved and kept his car back on the road.
Drive carefully and just watch out for and give way to those reckless drivers.
Have a Great Holiday! Cool Air and relaxing feel.