Aloha-
The San Pedro and YO-257 are basically right next to each other (approx 150 ft). The YO is in better shape than the San Pedro, but both have an amazing amount of life on them. In good conditions (little or no current) you can easily do both sites on the same dive. There is a couple of small resident white tips on the San Pedro - a bunch of turtles on both wrecks. A bit more as far as schools of fish go on the YO-257. The YO is my #1 favorite on the island. Sea Tiger is # 3, & 100 ft hole is my #2 (not far from YO & San Pedro).
The Sea Tiger is a much bigger wreck. It was only sunk in 1999 (YO was sunk in 1988) so it does not have as many differents schools of fish or the number of turtles as the YO or SP yet, but is still a great dive! It is in pristine condition & I have seen many more eagle rays & brown stingrays there- Also great Nudi's on the hull, leaf scorpion fish, octos and more. It is MUCH better for actual penetration- but I do not suggest that on the first dive there. It is also a bit deeper with a max depth around 120ft.
In most cases- chepar is right, Kewalo Pipe is normally the second dive. It is fun with a good variety of life. Also- very easy to navigate! It is simply an old pipe running north and south- but a good guide
will take you to flat reef, arch reef, or horseshoe reef (air consumption permiting)
As far as Pearl Harbor Wall- I am unaware of any operator that is currently providing services to that area. In fact due to the new homeland security act- they might not be able to access that site. Although I am not 100% sure on that- I will ask around and repost if new info on that is available.
I just so happen to know a dive operator that does night dives every wednesday and saturday night- to the YO or Sea Tiger
~ If everybody on the boat is in agreement I have seen it go out on 100ft hole for the 1st dive and San Pedro for the second.
If you have any further questions- please don't hesitate.
Enjoy
Chris Wade
Pacific Paradise Divers