The creation of a new brand is not something any company undertakes lightly. While I was not privy to the actual creation of the name, I can certainly make an educated guess as to a thought process that would lead to what Marriott ended up with it.

As a hotel chain, what do we at Marriott represent (or want to represent) to our guests? First, it can be assumed that anyone using Marriott's services are not at home. They are, by definition, on some kind of a trip. Marriott wants to be associated with good feelings on that trip. What are some of the ways people indicate a desire for someone else to have a good trip? "Happy Trails"? Right track, but probably too casual - especially for some of the higher end brands. "Fare Well"? Nice sentiment, but not really specific to travel. "Bon Voyage"? Hmm... Definitely implies travel, not just going home. French - always good for a boost in implied status. Let's work with this.

Ok, so Bon Voyage is a bit generic - no trademark opportunity here, so what can we do to make it "ours"?
Easy fix - drop the space. One word "BonVoyage" might get us past the trademark folks, but it still doesn't feel right. Bon Voyage is still a bit old-fashioned, and we want to be newer. Hip. But not too trendy. We want this brand to be around for a long time. Ageless. Yeah, that's it. Age-less. Let's take the "age" out of BonVoy/age/.

Ok. BonVoy. Not a real word, so trademarking won't be a problem. Now, how to make it look. We do want to be modern, so a nice clean font will do. So let's try this out.
Hmm, good testing, but people are having trouble with the pronunciation. The second O is long, so we can indicate that. But let's be a bit creative, and put the bar under, rather than over, the O. Clean, accessible colors.
Ok, we're good. Release the legal and marketing Kraken.

Marriott Bonvoy is a Go for Launch!