There are many reasons why I do the majority of my researh, in Salt
Lake at the Family History Library.
1. You have access, to all the films that the FHL has. All the films
that your local Family History Centers can order, and also all the films
that are restricted to Salt Lake only.
2. The films that are off-site (vault), you can always order them into
the library. There is no charge, to order the films, from the vault.
It usually take 1 or 2 days, to arrive. Also, the films then stay in
the Library. Because technically, all the films that the FHL has should
be in the Library. But until a need is shown for the film, it is kept
in the vault.
3. There is help desk, on each floor, where you can ask questions.
And usually there is someone who can answer your questions. Also, for
with Mexico research, there is Sister Ruth Schirmacher who is an
Accredited Genealogist, for Mexico on staff. She can be great help.
4. Also, you have access, to all the books, that are in the FHL