Starflower, this quote seems to indicate that Samwise
did pass over the Sea:
The Lord of the Rings: Appendix B, "The Tale of Years", "Later Events Concerning the Fellowship"
1482: Death of Mistress Rose, and wife of master Samwise, on Mid-year's Day. On September 22 Master Samwise rides out from
Bag End. He comes to the Tower
Hills, and is last seen by Elanor, to whom he give the Red Book afterwards kept by the Fairbairns. Among them the tradition is handed down from Elanor that Samwise passed the
Towers, and went to
the Grey Havens, and passed over Sea, last of the
Ring-bearers.
Also, I would offer this reason for the
Hobbits Bilbo,
Frodo and Samwise being allowed into
the Blessed Realm:
The
War of Wrath, in which
Morgoth's
armies were utterly defeated and then captured, was led by the
Maia Eonwe (who was
Manwe's herald). Eonwe was, therefore, an emmissary from the Blessed Realm.
During the War of Wrath all Morgoth's forces were destroyed, except for Morgoth, a few
Balrogs,
Dragons and
Orcs, and of course, most importantly,
Sauron.
Eonwe made the glaring mistake of not capturing the arguably the most powerful Maia Sauron, another whom should have been chained and cast out beyond the confines of the World (if he was not destroyed in the War of Wrath).
If Eonwe had not left in such a hurry after
Melkor was chained, he would have captured Sauron, or destroyed him. This would have meant no downfall of
Numenor or Last Alliance. It would have meant that basically none of the terrible things that happened during the Second and Third
Ages would have happened.
It would have meant no Ring of Power!
It can be considered, therefore, that it was Eonwe's mistake that led to the Hobbits ever having to suffer bearing
the Ring in the first place. And a mistake of Eonwe is a mistake of the
Valar, indeed all who participated in the War of Wrath (The Valar, the
Maiar, the
Vanyar, the Teleri and the
Noldor) are partly responsible. So basically all the
Ainur were accountable.
I think that the Valar wanted to attone for this mistake by giving all the Ring-bearers the chance to heal the hurts that the Valar were responsible for. It was their obligation to do this. If Sauron had been captured, none of this would have happened, and it was the Valar's responsibility to account for Sauron. They did not do this.
So I think that the Hobbits being allowed to go to the Blessed Realm was something that the Valar
had to permit.