The main road is US 1. If you go south of Ft. Lauderdale you'll quickly get to Dania Beach. You take the Dania Beach Blvd. over to the beachfront and it's a very nice, laid back, natural setting. It's much nicer the the crowded crazy Ft. Lauderdale beach IMHO. It's the only beach I would go to to hang out, relax and rollerblade on the boardwalk. Dania Beach is also known for it's antique shops if you're into that.
But if you want the exciting beach, go to Ft. Lauderdale Beach. Just a couple blocks north of Las Olas Blvd. (one of the main roads over the intercoastal waterway) is Beach Place. There's a bunch of shops and restaurants there, and some smaller shops along the oceanfront there.
Another nice spot is a little north of there at A1A and Comcercial Blvd. (another main road over the intercoastal called Lauderdale by the Sea. There's a few nice little restaurants and a beach area with a big fishing pier. It's a decent laid back place.
Also in that area is Birch State Park. I never went in there, but it's supposed to be nice. And there's just a ton of other small interesting things you can check out. Sometimes families take their kids to the Ft. Lauderdale port to see all the cruise ships. It's the busiest cruise port in the world. They have day cruises to the Bahamas and evening gambling cruises if you're into that. Also, the Hard Rock Hotel and Casino is very close (where Anna Nicole Smith died). The only bad thing is they don't have blackjack, my favorite. You have to go on a boat for that.
A trip to the Everglades to see some alligators is also a lot of fun. you can go on a fan boat and/or what they call a "swamp buggy" which looks like a monster truck/school bus mix. It's a lot of fun and you see a bunch of animals. While you're out west at the Everglades, you could stop by Sawgrass Mills mall. Even if you're not into shopping, it's just a cool place to visit. It's gigantic and has a lot more than just stores. A lot of people go there to eat at the outdoor-style restaurants or go to the clubs or movies.
Anyway, I could go on forever. But that's a few highlights.