All the beach clubs (see my rundown after the jump) seem to have a mix of families, singles, and couples; usually they consist of several subdivided sections, each with pools and a restaurant, so you can pick one that's right for you. And keep in mind that many turn into amazing nighttime beach/pool bashes (check the schedules).
The Riviera: Hands down the best beach club in Beirut. A must see. If you're visiting on the weekend, go before 11:30am to ensure you get a chair. You can rent towels or bring your own. They have several pools, a good restaurant, jet skis, and more. The crowd is fashionable and well to do. Go!
St George Yacht Club: A good runner-up to the Riviera, but it could use a renovation (and that will come when the owner reaches a settlement with the government). No beach access.
La Plage: Also in town, this club is a bit more formal, and smaller, but still very nice. No beach access.
Eddesands: Don't miss this one! Eddesands is a gorgeous club, with pools and beach access. It's about 40 minutes north of Beirut. Take a hotel taxi (don't pay more than 40 dollars, each way, and make sure the car has a/c before you get in it). The club costs about 14 dollars for the day and it's worth it. Pick the Paradiso area and have lunch at the eponymous Italian restaurant, or at La Peche du Jour (for Lebanese and seafood). Near the main entrance of Eddesands is a hotel and spa, in case you want a massage. I'm told some people fly into beirut just to spend the weekend at this beautiful club.
Oceana: Located in the south, this club has family areas and also the La Suite section for trendy young people (it happens to be the nicest section). Sundays at La Suite turn into a major party scene by mid afternoon. I heard good things about nearby Pangia, but did not have time to visit.
Note: The sand and beach are alluring, but watch out for sea creatures that might sting. I got one (minor) sting.
A day trip to the Bekaa Valley is highly recommended – I did this to break up the beach outings. Hire a private car for the day (about 80 dollars) and the driver will take you to Balbaak, whose ancient ruins date to Roman times. This archeological site is as significant as the Parthenon in Greece, Petra in Jordan, or Pompeii in Italy. Guides on site can provide a one-hour tour (20 dollars). In summer Balbaak has a famous opera festival.
By the way, at the entrance to Balbaak, don't miss the Hezbollah memorial. The display is a good dose of propaganda as it ignores a great many political facts, but it's worth popping your head in. There are displays and photos honoring this anti-Israel movement. While Hezbollah is strong in Lebanon's south and in the Bekaa Valley (as evidenced by banners supporting the group), and is known for the social services they provide to the poor, they're also disliked by a great many Lebanese (especially non Shiites) for their militancy.
After touring the temple sites, we drove on to Zahle, where we had lunch at the Arabi Hotel – excellent food and a pretty setting on a river.
Carry on then by car to Chateau Ksara, a wonderful winery. Take the tour, sample some amazingly good whites, reds, and rosés, and buy a bottle or two – great prices for excellent vino. My favorites were the Blanc de Blanc white, the Gris de Gris rose, and the hearty cabernet. These were all priced at just about 7 dollars each!
I went from here to the Syrian border. Having a few glasses of wine prior to crossing via land is not a bad idea.
Up next: Three Days in Syria