This year, I was doing an MR through RDU, and I walked off a plane, hung out at the airport for half an hour, then walked back on. The FA did a double take and said, "You're back?" I just sighed and said "Long story." It was also felt like a "walk of shame" - I was in 1st on the way in, but had to sit in coach on the way out.
I actually don't like seeing the same crew in and out. It just seems weird to me - I feel like I owe the crew an explanation. On the same MR, (RDU-SEA) I actually could have gone standby for a flight in SEA that was same metal as my inbound, but I chose to wait an hour and go on the next flight, just so I wouldn't have to do that. :shrug:
I like to spend a few days in a new place (especially international). I spent one night in FRA and ended up with the same crew both ways. One of the FAs asked me something like, "You're headed back already?" That one I was able to skirt with, "Yes, just a quick trip."