Cajun Chris;
My wife I spent a lovely vacation back in the 1990's, don't recall exact year now, in Lafayette LA. Sure enjoyed chowing down on that "Crawdad" etoufee & alligator tail. Went down to Avery Island & toured the Tabasco plant & also saw the Egrets nesting there. Took a nice boat tour of the big swamp north of Lafayette, can't recall how to spell it now, but semi remember how to pronounce it. We have a town here in East TN with the same spelling as Lafayette but folks there call it La-Fay'-ette rather than Laf' ay-ette. Don't know if I got those accents exactly right, but anyway it's pronounced totally different, sorta like folks in Southern IL call Cai'ro, Karo. Would love to make it down again, but just don't travel much anymore.
Glad you had a good time. Lafayette and the surrounding areas has a bunch to do there and I think Avery Island is one of the best. Vermillionville is another one. It is a collection of buildings saved from around the area. Vermillionville is the original name for Lafayette.
I have two theories on the pronunciation. The French language was systematically stomped out by the government. Schools would beat my grandparents for speaking French even though French was spoken here well before English. Cajuns were discriminated against and not thought off as Americans. Sooo, I think they started mispronouncing Lafayette.
Second Theory is that since Lafayette is an oil town the Texans that showed up mispronounced the name. You know how they are. And since we didn't want to embarrass them we just started mispronouncing it.
If you do get a chance to come back, I suggest visiting Baton Rouge, New Orleans, and then Grand Isle. You will get a chance to see three different cultures. Baton Rouge is more like a big small city. More English than French. New Orleans is Creole but had the highest Italian population for awhile. Even more than NYC. Finally Grand Isle is saltwater Cajuns. The fishing is great.