I highly recommend a cocktail at Farquhar's Bar (tel. 04/222-2000; daily 11am-11pm), located within the old E&O Hotel, from where you can tour the areas of the hotel that are open to the public. Across the street from the E&O, Upper Penang Road has an entire strip of shophouses dedicated to nightlife. Here you'll find pubs and discos; beer gardens and live music; good beer on tap; and patrons from Penang's local, expatriate, and tourism populations. Possibly the most notorious bar in Penang is the Hong Kong Bar, 371 Lebuh Chulia (tel. 04/261-9796), which opened in 1920 and was a regular hangout for military personnel based in Butterworth. It has an extraordinary archive of photos of the servicemen who have patronized the place throughout the years, plus a collection of medals, plaques, and buoys from ships. Be warned, it's a real dive bar.
If you're at Batu Feringgi, the best party is at the Hard Rock Cafe (Hard Rock Hotel, Batu Feringgi Beach; tel. 04/881-1711; daily 11am-2:30am), which has live music nightly. There's a cover charge of RM30 per person, which includes one drink if you come on Fridays and Saturdays after around 10:30 -- if you come earlier, the restaurant serves decent burgers.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.