Anyone who has shot both have any opinion on which of the two would be a better overall buy for a first Beretta?  I like the looks of the Brigadier a little better than the standard 92 FS but I read on this board that the slide was a little thicker which might make purchasing holster accessories a little more difficult ...  What about function?  I would guess that they are pretty much identical ... So, anyone with experience on both care to share their opinion?

Don't worry about the heavier (thicker) slide.  I haven't had any problems with holsters or accesories.  I have an old 92FS and a 92G Elite II with the brigadier slide.  I definitely prefer the heavier slide.

You could fit a Brig into a looser holster either by getting a bigger "one size fits most" one, or by streching out a leather one.  I carry my 92 with a hard plastic form fit holster that I know for a FACT that Brigs won't fit into (I tried to holster a friend's one just for S&G's, and it was a no-go).  Get what you like and worry about the details later.