smart way of saying at the end of the day?

when all is said and done
when the shouting is over and the lights go out

Midnight

I'm assuming you mean the figurative expression, not the literal end of the day.

When all is said and done
In the long run
In the end
Ultimately
When push comes to shove (depending on context)

People used to say, "In the final analysis."

It depends if you mean literally or figuratively. If figuratively, then 'ultimately' would be the word you want.