Gimli was allowed to go to Valinor despite not being a ring bearer. Is this explained in detail or just with the one line "for his love for Galadriel"?
There's not much detail about this aside from what's said in Appendix A to Return of the King:
We have heard tell that Legolas took Gimli Glóin's son with him because of their great friendship, greater than any that has been between Elf and Dwarf. If this is true, then it is strange indeed: that a Dwarf should be willing to leave Middle-earth for any love, or that the Eldar should receive him, or that the Lords of the West should permit it. But it is said that Gimli went also out of desire to see again the beauty of Galadriel; and it may be that she, being mighty among the Eldar, obtained this grace for him. More cannot be said of this matter.
And Appendix B:
Then Legolas built a grey ship in Ithilien, and sailed down Anduin and so over Sea; and with him, it is said, went Gimli the Dwarf. And when that ship passed an end was come in the Middle-earth of the Fellowship of the Ring.
And Letter 154:
But in this story it is supposed that there may be certain rare exceptions or accommodations (legitimately supposed? there always seem to be exceptions); and so certain 'mortals', who have played some great part in Elvish affairs, may pass with the Elves to Elvenhome. Thus Frodo (by the express gift of Arwen) and Bilbo, and eventually Sam (as adumbrated by Frodo); and as a unique exception Gimli the Dwarf, as friend of Legolas and 'servant' of Galadriel.
There are a few things we can deduce from these brief comments:
- It's notable it "it is said" that Gimli went to Valinor, and that the main text (from Appendix A) is very non-committal on the matter. It may well be that Gimli didn't actually go to Valinor after all.
- The Letter text treats it as if it actually did happen, and notes that Gimli was "a unique exception".
- The Letter text also notes that this is granted to mortals who have played a significant part in Elvish afairs, thus ignoring the reason (very explicitly stated in multiple other places) why Bilbo and Frodo went: for healing.
- It therefore seems that we shouldn't take the Letter text too seriously; it may well be a passing idea that Tolkien had but which is not in accord with what he wrote elsewhere.
I am going to belatedly provide a nitpicky answer:
Gimli did not go to Valinor.
Neither did Frodo, Bilbo or Sam.
They went to Tol Eressea, where presumably they would live out their lives, Galadriel's song "Namarie" notwithstanding.
Somebody who has the Letters handy may even be able to quote verse and chapter, nagging in the back of my mind, where Tolkien stated that. Even something about the Noldor generally only moving to the Lonely Island, possibly Tirion or Alqualonde.
We can speculate that they were permitted to briefly visit Valinor and have something like an audience on Taniquetil with the Valar. Get a nice pat on the head for defeating Sauron. Maybe Gandalf, reverting back to being Olorin took everybody on a visit to Lorien. Who knows?
It's been a gripe of mine for a while here of SFFSE as it's generally conflated: Valinor is the lands of the Valar in Aman. It's not "the West" in toto.