Being that I want to relocate there, I'm a bit biased and found Ft. Lauderdale Beach to be the perfect balance of a metropolitan beach life! The long stretch of concrete wall (you can just step over it) is great for viewing the beach or the cars/motorcycles, depending on which way you're facing. Straddle the wall and you get both views! There are a good amount of restaurants and shops and the locals are friendly so you get more smiles than in New York.
It's only half an hour away from South Beach Miami and the airport is easy to navigate and is busy enough that you can get good travel deals flying from/to there.
Unfortunately, I did not have enough time to go to Las Olas, but I hear it is really beautiful. I'm definitely going back for that!
Oh, unless you have a wonderful friend who can drive you around, it's a good idea to arrange renting a car for further exploration!