8 dives? Are you going for a day and a half? I did 48 dives between Truk and Palau in a 2 week period.
Blue Corner
Blue Holes
Saies Tunnel
Ulong Channel (timed with a full or new moon tide).
Chandelier Cave (hopefully the 3rd dive of a day and not counted towards your 8)
Jellyfish Lake (once again not a real dive)
Yellow Wall
Peleliu Cut
The above 8 are solid. Blue Corner and Blue Holes are musts, and I thought Saies Tunnel and Ulong Channel were great, too (Ulong Channel was a FUN ride, we hit it on a really good tide).
Jellyfish lake is okay. Its certainly different, but its a snorkle, not a dive. You have to stay above 15 feet.
On the Blue Explorer, we did Jellyfish Lake, Chandelier Cave, and Mandarin Fish Lake as the final 3 "dives". Chandelier Cave is very cool, but you aren't going to go deep (I think it bottomed out at 35' at the deepest). Mandarin Fish Lake allows you to do the "Emergency Stand Up" just in case you run out of air, you'll basically be at 15' or less. Those 3 plus a wreck dive made for a good last day of diving, its pretty hard to get much nitrogen built up before your plane flight on Nitrox 33 at the depths of Chandelier Cave and Mandarin Fish Lake.
My most memorable dive in Palau was German Channel. There are a pair of cleaning stations where Manta Rays get cleaned. We hit it just right, we had 5 Manta Rays circling our group at 15'. Its apparently hit or miss, if you hit it right, the Mantas are awesome.
If you're going down to Peleliu, Peleliu Express is pretty similar to Blue Corner, its worth it. Orange Beach was also pretty cool in Peleliu. Keep in mind that if you go to Peleliu, that's going to be your whole day, so the reality is that you're going to do 4 dives there, you won't be able to match 'em up with dives in other locations.
Big Drop Off has some stretches of nice soft coral. Its in the stretch with Blue Corner and Blue Holes - if you're going piece meal, you may not get a choice if you're doing Blue Corner and Blue Holes, Big Drop Off may be a mandatory part of your itinerary.
If you're into it, you might want to consider doing some of the wreck dives. The one I dove (I think it was the Aibo, I don't have my divelog handy) was nice, albeit not as good as what you'll see in Truk.
