[Maédhros]

I'm confused. Are you saying that her link with Thingol is what bound her to her body, or are you saying that it is what allowed her to leave it. If the former, then I disagree. If Melian was bound to her body, then it was because of how she used her body not because of her link to Thingol. If you were saying the latter then I would say that it is a possability, but it is my opinion that when Thingol died her link to Middle Earth was severed and her link to her body went with it. Also there seem to be degrees of incarnation, Melian may have been incarnate to some extent, but certainly not as much as Sauron was.

What I'm saying is that there indeed was a link with Thingol that made her incarnate herself and be with him in ME. I'm very familiar with Melian after Thingol died because that is something that we are currently working in the Project. It is my opinion that when Thingol was slained, Melian went to Ossiriand first to warn Beren and Lúthien about what had happened in Menegroth unlike what it is told in the story in the Published Silmarillion.
I have to strongly disagree with the level of incarnation of Melian and Sauron. Melian is definitely more strongly dependent on her hröa than Sauron. Why? Because she even had a child in that union.
From Ósanwe-kenta

"We do not know the axani (laws, rules, as primarily proceeding from Eru) that were laid down upon the Valar with particular reference to their state, but it seems clear that there was no axan against these things. Nonetheless it appears to be an axan, or maybe necessary consequence, that if they are done, then the spirit must dwell in the body that it used, and be under the same necessities as the Incarnate. The only case that is known in the histories of the Eldar is that of Melian who became the spouse of King Elu-thingol. This certainly was not evil or against the will of Eru, and though it led to sorrow, both Elves and Men were enriched.

About Sauron reclothing himself, remember that he was not incarnate until after the destruction of Numenore. The Ealar's power was lessened after their bodies were destroyed even if they are not incarnate, but far more so if they are. The first time Sauron's body was destroyed he was hurt only a little. The second time was much worse, just like Morgoth he had done horrible evil and he had dispersed much of his power (the Ring). Also there was the weakening of his power due to his body being destroyed. This resulted in his becoming incarnate. So when the Last Alliance came there was a different story, this time he was incarnate and so became nothing more than an impotent (or nearly so) spirit (there is no record, that I can recall, of any Maia, other than Sauron, who came back after being "killed" in incarnate form, save maybe Gandalf, but he seems to have been a special case also). However, the Ring is what saved him, it "anchored" him so that, slowly, he was able to rebuild a body. Just as his Ring was his savior so it became his bane, for when it was destroyed his anchor was lost and so was he.

Are you implying that Sauron was a mere spirit and not incarnate during his time in Númenórë? That of course is just wrong.
From Akallabêth The Downfall of Númenor

For Sauron himself was filled with great fear at the wrath of the Valar, and the doom that Eru laid upon sea and land. It was greater far than aught he had looked for, hoping only for the death of the Númenóreans and the defeat of their proud king. And Sauron, sitting in his black seat in the midst of the Temple, had laughed when he heard the trumpets of Ar-Pharazôn sounding for battle; and again he had laughed when he heard the thunder of the storm; and a third time, even as he laughed at his own thought, thinking what he would do now in the world, being rid of the Edain for ever, he was taken in the midst of his mirth, and his seat and his temple fell into the abyss. But Sauron was not of mortal flesh, and though he was robbed now of that shape in which he had wrought so great an evil, so that he could never again appear fair to the eyes of Men, yet his spirit arose out of the deep and passed as a shadow and a black wind over the sea, and came back to Middle-earth and to Mordor that was his home.

He was definitely incarnate in Númenórë.
From The Tale of Years

Sauron is taken as prisoner to Númenor; 3262-3310 Sauron seduces the King and corrupts the Númenoreans.
3319 Ar-Pharazôn assails Valinor. Downfall of Númenor. Elendil and his sons escape.

So we have that Sauron spent aprox. 3319-3262 (57) years in Númenórë as an incarnate.
Can you imagine Sauron not being incarnate while in Númenórë. They would have freaked out at talking to a spirit I think.
A bigger point is this. How can anyone know that Sauron wasn't incarnate the whole time that he was in ME? If Melkor his master decided to be one, it would be logical that he his lieutenant would follow his master too.