Not The Best of Times Because, Why?
Kevin Drum posts this chart as a one-picture refutation of McCain's statement that we are living in the best of times.

Um, OK. We all got wealthier. And the problem is, what? That someone else got even wealthier than I did? So what. Do we really have to keep refuting this zero-sum economics-of-envy argument?
I won't get into the whole zero-sum thing, because the chart itself proves that the world can't be zero-sum, since everyone got richer on average. But here is a full refutation of zero-sum wealth arguments. Also, a zero-sum wealth quiz here.
Looking at changes in income brackets is
always misleading. In the US, most folks are migrating up the brackets
as they age and gain experience. So most folks benefit not just from
the increase in their bracket but a migration to the next bracket.
To this last point, the bottom end of the bracket is being flooded
with new immigrants (legal or not) with poor skills and often no
English. They drag down the averages, again understating how well the
typical person is doing. Lifetime surveys of individuals rather than percentile brackets always demonstrate that individuals gain wealth over time much fast than this type of analysis demonstrates. And even the new immigrants at the bottom are presumably gaining vs. their previous circumstances, or else why else would they have immigrated in the first place.
Here is an alternate response to whether we are in the best of times.
By the way, here is an interesting article on why using a single inflation rate for the poor and the rich to get real income growth may be incorrect. There is an argument to be made that the poor have a lower inflation rate than the rich, thanks to Wal-Mart.