My wife and I lived on Penang and revisited it a few years ago. It's a magical island and when we were there last did not strike us as being particularly expensive. The beaches are superb and there are many interesting places to visit. Go for it !!!
We went a few years ago, KL then over to Kuantan.
If I went again I would do a short trip to the Highlands. Trengganu is supposed to be lovely.
Generally the east coast is very undeveloped and not geared up for tourists or it was when we were there. I would head for Penang and maybe go and see the Bridge that the Allies built over the Kwai
Penang is touristy and grotty in the local 'kampongs' (housing estate). It's getting islamitised and you could have a mosque near hotel chanting out at 5am. Lots of stall-shopping for fake designers goods. Food stalls okay, watch the cooking though - else it could be the imodium!
Russians & Arabs have found the 4-5* hotels & they bump up prices. Dont swim in the sea as its full of stinging jelly-fish. Mossies are a nuisance so cover up at dusk.