Whereas Waikiki beaches tend to be packed with oiled-up tourists, just a few minutes away the Ala Moana Beach Park has a decidedly different vibe. This area tends to be favoured of the locals, and during my stroll along the beach I noticed many family get-togethers and work events set up under tents, hundreds of people young and old enjoying picnics and mid-day barbeques.
In the season 6 episode Everybody Loves Hugo, Hurley and Libby finally enjoy the beach date that was so rudely interrupted by Michael back in season 2.
I'm fairly sure that the 2 screenshots above are taken along the narrow portion of the beach which runs along Ala Moana Boulevard. The first shot of Libby below also looks to be at Ala Moana, though possibly a little closer to the Waikiki side. I'm not so sure of the final screenshot below -- the background doesn't seem to match my memory; probably it is either CGI, a different location, or a brain fail on my part.