If it makes any difference, I always make a point of smiling and being nice to the airline staff (both in the air, and on the ground) - and don't do it in the hope of getting free things or special treatment, but because I have a friend that works in the airline industry, and I hear many tales... some of the rubbish they have to put up with from passengers is just atrocious, and I wouldn't ever want to be like some of those people!
Plus, a few manners never hurt anyone
I probably should also mention that, with the exception of one flight, I *always* sit in the exit rows when flying long haul economy, and often chat to the crew if they seem interested... I never ask for (nor expect) any special treatment when travelling in Y, though I'm of course very grateful for the handfull of times that the crew have gone out of their way to look after me (whatever their reasons may be).