Personally I'd love to see Hitler in heaven and have a beer/wine with him. I'd assume he'd met with suitable punishment - and that all sins were forgiven. And all those people who had wronged me personally...there'd be no agendas in heaven so it would be awesome to hang out with them.
Biblically though, it's a sticky wicket, if I have any sense of inate morality then any God who was the ultimate judge and was also most merciful, would run a heaven scheme as above. I'd be expecting, and would welcome, any punishment under such a God.