I feel that in the end, the deeper point will be Eastern in it's view (we are talking about the Dharma initiative after all). The interracial couple of Rose & Bernard are the only ones in the whole show who are happy in either reality, & both before & after the crash. They simply live life & relish in all that it brings.
The scene where they found them in the jungle was no small hint. The team was running around trying to save the world, & in the end they had all lost sight of the fact that their lives were actually better 'because' they had landed on the island. The couple (one black & one white - displaying yin & yang, etc) had finally settled in to simply see things for what they were & find a sense of harmony in it. In that, they came back to the same place of peace & happiness they had before the island.
Also, if you remember the only time they were both unhappy was when they were apart (you can't separate yin from yang). Thus, peace & tranquility is found in the balance, the joining of the two & this is the place where all comes together & love ultimately shows you the way to a state of eternal peace.
Locke was the crusader - feeling that he was being guided by some great all powerful force & was destined to achieve something great (the atypical hero quest on a grand crusade in the name of God). In the end, however, he was the most sad character of the bunch, for he was nothing but a mark for everyone around him. He was the voice of Destiny, but ended as a dupe.
Jack was the guy who wanted to save the world & lead everyone to his cause. But he was so caught up in his mission of 'saving' everyone that he lost perspective of the bigger picture or seeing things for what they really were. In the end (or beginning of the end), he succeeded but what he really did was to screw everything up. He was the voice of Free Will (we can change this), but in the end just screwed it all up.
The rest are almost all an endless parade of diversion & distraction w/ a few subtexts & lessons along the way (such is life I guess). Ultimately, they are the world, running around caught up in the ebb & flow of forces around them.
But in the end, there is, quietly off to the side, the one couple who were completely happy w/ one another. They were lost for a while & that brought some discontent - even themselves for a time being caught up in the trials of the moment. But in the end they came realize who they were & that their sense of true happiness was really found in each other. As a result, they had all they needed & then took things as they were.
This too is a subtext for what's going on. Remember, Jack wanted everything back because he couldn't have Kate. Sawyer thought it was a bad idea because he had his affection.
But Rose & Bernard simply found bliss in each other & thus happiness even in a world of chaos. In this we will later disciver that it was these two who were Adam & Eve in the Cave.
There's a lot going on & it will be interesting to see how all this comes together & wraps up.
Rick~