Hello. I am curious to see what you do when this happens to you, both pre-flop and flop. Anxious to see your answer. Thank you.
This depends on a few factors for me
1) How deep are the stacks (if it's less than 40 big blinds i'm usually all in no matter what)
2) What position is my opponent in (if it's an early position battle I'll be more cautious than a late position or button vs blinds confrontation)
3) What type of range do I think my opponent would get it all in with (most opponents will get it all in with a wider range than just KK AA, which is why it's usually safe to get it in)
I always ask myself "could my opponent put all his money in here with a worse hand than I have?" and base my decision off that.
There are a few rare instances where I'm ok with folding these monster hands. Example would be in a live game 300 big blinds deep, or in a pot where 4 people are all in for 100 big blinds. But these are very rare scenarios.
If I'm concerned about that type of situation coming up then I'll often just flat call the open or 3-bet rather than reraising. This pretty much eliminates the possibility of facing and all in bet preflop, and enables me to get more information after the flop to decide if my hand is good or not.
Hope that helps!