Hi Clipper, want to throw in a favorable comment for Penang. First time there after way too many years, spend three days there, just got home tonight. Although there's some some construction coming up, the Unesco recognition for the Georgetown area is completely deserved. If you're into culture and history, just walking around is eye opening. Having lived in Singapore for nearly 20 years, I can appreciate how Penang might just reflect what Singapore might have been 30 or 40 years ago. It's a slower paced town than HKG, BKK or Tokyo, people generally friendly.
Jiejie (who always gives good advice) made a useful suggestion of going from Singapore to Johor Bahru (JHB)for the flight to Penang. This can be done; I did it to see what it was like since I go up to Johor Bahru a lot just for shopping. But I'd say, don't do it unless you have time to kill and you want to explore another city, plus you want to have a flashback to the nastier parts of Manhattan in the 70's (not nice). The airport is in Senai which is another 45 minutes from Johor Bahru (we call it JB for short) town center. There is an airport bus that leaves from the Kotaraya bus terminal in JB, but you need to find it (for record's sake, Singapore Bus Services bus 160 from Singapore goes there directly after Malaysian Immigration). I flew back to SIN from PEN directly and found that much more straightforward and much less stressful.
For the other poster that suggested that Malaysia should be off your list because of the church bombings, that suggestion just isn't supported by the facts on the ground. Over two days and nights of walking around town, going to hawker centers for meals and glitzy shopping centers, I'm seeing the full spectrum of Malaysia's various ethnic and religious groups intermingling and buying stuff in a more integrated way than I've seen in either JB or Kuala Lumpur. If there were insurrections in the streets we be seeing shops with their gates rolled down against maurading hordes of crazed locals. That was precisely what was NOT happening. To the OP that suggested that Malaysia should not be visited, you really have to judge the situation on the ground in person, not just rely on what somebody else's news broadcast says to make an interpretation.
Clipper, just know that I grew up in NYC in the 60's and 70's and still know NY well; believe me when I tell you that my NY survival instincts did NOT kick in when I was in Penang this weekend. Hope you enjoy your visit to this part of the world!