Bejamble, to answer your question on the best salt water beaches in the USA: Some rules of thumb I've found to be consistently true, for when it comes to RING ratios. Ie.: rings to coins and other targets:
a) warm water beaches. If the water is warm enough to swim, and lots of people go into the water (without neoprene wet suits), then the ring ratio goes way up. Where I'm at in CA, not many people go in the water past their knees, since the waters are simply too cold. However, further south (say, south of the Santa Barbara line), the tropical currents keep the waters warm enough that you can swim w/o a wetsuit, most of the year. Where I'm at, perhaps only a single month of the year, and only then-so following long hot spells, and only on a single few shallower beaches, can you enter the water without turning blue

Thus the southern CA guys seem to get the higher ring ratios. This same phenomenom would hold true for other states waters.
b) tourists versus "locals only" feel. If the beach is more of a locals feel (dog walkers, joggers, etc...) then ring ratio drops. But if it's got hotels, restaurants, and lots of out-of-town folk-tourist draw, then the ring ratios increase.
c) Honey-moon tourism draws: If the location is not only a draw for travellers and out-of-towners, but specifically honey-mooning destinations, then add another plus to ring ratios. Because someone who's just gotten married, is theoretically wearing their rings for the first time. Hence not used to it yet (size-fitted properly, and so forth, not accustomed to the feel yet, etc...).
d) demographics of affluence: If the type tourists tend to be more upscale (golfing destinations, high-brow expensive destinations), then seems jewelry ratios also go up. As opposed to low-budget "motel 6" type hotels dotting a beach-side. Or even if not affecting the ring -ratio, can certainly affect the caliber/value of the ring types, eh?
e) lack of other hunter competition. Obviously if not a lot of persons are into the hobby in a given locale, well ... then .... targets will accumulate more over time.
Hey, and if you think of it, Hawaii seems to score on all those counts, eh? Except for the last point, haha