Just to add to Raptors gouge...
There is a bonus to the interaction with the flight deck in the way of a "field upgrade" (space permitting). However, I make a point of always stopping in at the duty free and picking up a large bag of candy (good chocolates) and after formalities with the front end I give the lead FA the goodies for the back end crew to share.
Most likely you won't see the pilots again inflight and as it is the pilots' mutual professional (reciprocal) agreement in the first place, we always think of it as an even trade, as they are free to get a JS from us too.
However, the appreciation from the FA's for the little token of respect you just showed them goes a long, long way no matter where you end up (near front or back). I have received more attention from the FA's in economy on some occasions with that small gesture of goodwill, than on some flights in Business Class.
Just a little trick to make the flight go really well for everyone...
Breathe easy...
