I make it an invariable rule to stop reading, wear my 'seeing' (as opposed to reading) glasses and pay attention to the safety briefing. I get comments from CC on often being the only one in business class who does!
If CC are going to the trouble of doing the brief, it's only polite to listen. It's also polite, I feel, to thank CC and Flight crew when disembarking.
I find it interesting the number of times CC seem surprised that an ordered special meal has actually been provided!