i'm just a PPL so never expect to be in this situation - however i once had to tell the cc on a flight we were about 2 mins from touchdown - I knew the approach + where we were, was sat in the back row and she was dawdling about in the galley - the usual 'crew seats for landing' call wasnt given.
Also I try to grab the emergency exit row when i fly - not just for the extra legroom, but to know that i have a chance of getting the thing open if it comes to it. Nothing winds me up more than pax in that row who have no idea how to open the exit and dont listen to the safety announcement or read the card - I always make the point of asking them if theyve read the card + know what to do....