From Beirut take bus #6 going from Cola station to Byblos (Jbeil). Ask to get of in Jounieh. It is possible to catch the bus anywhere on its route, including at the Barbir intersection in central Beirut. The ride takes between 20 to 45 minutes depending on traffic and costs around 2,500 LL.
From the Rafic Hariri International Airport your best bet is to take a taxi for around 25,000 LL.
You can do anything at night ranging from visiting the city's several restaurants ranging from Italian to Japanese cuisine or just sitting at a coffee shop to relax and have some narguileh or visiting the bars and clubs at around 11pm and up