BRS-FRA is EW operated, and whilst the aircraft (146) is always pretty consistent, the crews vary between being borderline grumpy and charming. I haven't spotted a pattern yet (no consistency to grumpiness on the 06:30 BRS-FRA, for instance).

I'm not sure where they are over-nighted, but I think they get a long stopover in Bristol (11:00 arrival, depart at 06:00 the next day / 22:15 arrival, depart at 11:50 the next day) so I assume they get enough sleep? Maybe they get fed up at being away from home for quite a long time. And I guess it's not really enough time to go sightseeing either.

LH Cityline seems pretty much like Mainline to me. I've only had one bad Cityline experience (LCY-FRA, a couple of Christmases ago), but that was a shocker. The only time I've openly rowed with a crewie.