One thing to bear in mind is your fellow passengers, I can't comment on Business or First class but my sister upgraded to PE on her honeymoon flight and said she was surrounded by sub-human scum, basically old OAPs who kept on farting and constantly making demands on the cabin crew as they were entitled to it all having paid a bit extra - you know the sort. I flew PE once and can confirm that although not as bad as my sister's experience, my fellow PE passengers were annoying retards - much more annoying than people in cattle class.
The thing about business class is that you expect it to be full of men in suits. If you're flying to New York, it is. If you're flying to Barbados, it's not - it's full of older, richer people going on holiday. You do get the occasional screaming kid too.