I would disagree with this one - my situation was quite opposite - I always liked the idea of flying business class but then I had quite a few chance to actually fly business and first class and didn't feel that much of a difference as compared to additional significant costs (either in term of miles or $s). So now I will fly business only in two scenarios: (1) it costs me nothing (either in terms of extra $ or miles) - i.e. my company pays for my ticket, I get a free upgrade or something similar (2) I have a critical activity soon after I arrive and being somewhat tired vs. a bit tired makes a world of difference (which is most cases coincides with #1)

So YMMV - I think it mostly depends of what travel is for you - if it's moving from point A to point B, coach can very well accommodate your needs, if you're all about getting a luxury treatment, boarding first and feeling "elite" compared to those seating behind you, first is the way to go.