So many variables. If...rain, snow, really cold nights are an issue, I’d go with tent with a floor. For those rare early fall nights in the mountains with none of those issues, you could sleep right on your air mattress. A simple tarp over your bag will keep the frost off you. I look at it, if I need a tent, I need a tent with a tent with a floor.
Nah, good floorless shelters do just fine in driving rain, hail, snow, and deep cold. It does take some strategy to pitch them properly for the conditions, though. I'll leave the creepy crawlies out of my statement, since that's a personal and subjective thing to some extent.
