The linked comments appear to be based on Air Canada procedures (as previously stated each airline has its own approach to them). However they miss out the most significant part of AC announcements, which is complete bilingualism.

Airlines based in bilingual countries are much more likely to go for prerecorded announcements to avoid language blunders by FAs in the opposite language to their native one.

In german they announce it meters (i've flown lufthansa, british airways, and continental to FRA)..

I experienced a first last week, singing of an announcement! It actually was well done on Alaska Air SFO-SEA. To the tune of "Beverly Hillbillies" the lead FA thanked us all for coming, etc. and continued on for several verses. I'm normally the last guy that would think this is cute, but she tied every line together with a rhyme plus had a good voice.

My peeve is the captain or 1st officer who really hate speaking on the microphone, but are forced to make at least one or two scenic announcements. You can sense the dread in their voices as they wake you from the cat nap you just began. Some guys are just not chatty or comfortable with small talk, why force them into an awkward situation?