Total Recall had a very ambiguous ending but no matter which way you spun it I don't think it really mattered if it was all a dream or real. I personally like that approach rather than leaving us anxious for answers.

For instance the Usual Suspects and its infamous twist ending was poorly handled as we are asking more questions at the end of the film than at the start. I had invested an hour and a half into this film and there is absolutely no conclusion to what actually had happend. God dammit I hate that movie. So overrated.

Great endings are ones that leave us wanting to know more but still leaving us satsified with what we already know. I'm sure everyone who watched the Breakfast Club would die to know what happened the next day but our imaginations can fill in those answers. Same thing with Dawn of the Dead, I would love to know what happened next but in all seriousness it wouldn't matter as everything before it had concluded.