try ko'olina
Ko Olina Resort & Marina - Honolulu Hawaii
it's gorgeous there! it's 4 different lagoons instead of just one expansive stretch of beach.
also, there is a church (or temple?) located on a hill behind the beach. i've seen a ton of weddings there, although only from the beach. i've also seen couples take their pictures in the lagoons. i don't know if it's free but it's worth a look, i think.
on a sidenote, a lot of japanese get married in hawaii because it's close to them, and they have this great tradition of releasing paper birds after the wedding and it was the coolest looking thing going over the water.