Seriously, I guess if you go to Penang then you should visit Penang Hill. However, I am not sure if one would like to go there more than once.
The queue to go up the hill, can get quite formidable. We went at around 1000, and had to queue around 20 mins to get a ticket and then another 30 mins or so to get on the tram. Those who came later will have a longer queue to 'enjoy'
Please make this a morning visit. On the hill, you can visit a few places, like the Monkey Pot garden (must go if you are on Penang Hill), Owl Museum and other places.
If you are not sure if you would like to go to Penang Hill, or if you are short on time.. then skip this.