All right, so as we all know, at the end of 316 while five of the Oceanic Six where headed back to the Island on board an Ajira plane, there was a white flash just before the plane actually crashed. We know that Jack, Kate, and Hurley all ended up together, near (or in) the lagoon where Sawyer and Kate swam in Whatever the Case May Be (and later where Nikki and Paulo swam in Expose).
What we don't know it what made these three special or different from Sun and Sayid? Why did they end up safe and sound and together?

And where the heck were Sayid and Sun, anyways?

At the beginning of The Life and Death of Jeremy Bentham Ilana told the newly-reserected Locke that she saw the pilot and a woman take a boat and leave the smaller, Hydra Island, and head for the main one.
What most of us assumed was comfirmed in Namaste - Sun was the woman who went with Lapidus in the outrigger.

But why didn't she flash along with the Jack, Kate, and Hurley? As we know, she, along with the other crash surviors (minus the rest of the O6) are still in the present. We can assume the others didn't flash because the Island didn't need them like it needed the O6... but why didn't it need Sun? If it was so important that they all come back, why was she left out?
Could it be that the Ilsand somehow "knows" about her connection with Widmore? Is Widmore really the evil mastermind Ben would have us believe he is? If Widmore would actually put the Island in danger, is that why Sun didn't flash? Is the Island punishing her? Or just protecting itself?

While we're on the topic of Sun, did anyone else notice that in Namaste she, Frank, and Ben we the only ones with cuts on their faces? Sun's cuts were all on one side ofher face - could that mean something?

Now for Sayid. As of Namaste we know that he did flash back to the '70s, but not with Jack, Kate, and Hurley. Jin found him wandering around in handcuffs after he tripped an alarm. After Radzinski found out, LaFleur was called and was forced to treat Sayid like a hostile (whereas the others were lucky enough to be part of the Dharma Initiative). Sayid was smart enough to keep his mouth shut and not ask questions as Jin and Sawyer kept their act up in front of the Swan-model-building Radzinski.
But why did Sayid end up away from the group? Again, what made those three special?

Will Sun end up back in the '70s? Will Sayid's secret be discovered? ...And where the heck is Dan??