This is the whole reason I fly for living now...
I went into the flight deck on an Air Malta flight in July 1987 and ever since, I was hooked. I was not bothered by the buttons and dials and how the plane flew, I was more interested in the view and now, I get to sit in the flight deck, well sort of, every flight I do.
I remember flying back from SFO, working down the back for a rare change, and a rather excitable early 30's chap came to ask if he could take his son up to the flight deck. We were on stand, waiting for something baggage related to be sorted and I could still see plenty of ramp activity, so called the flight crew:
BBB: Hello Capt. its BBB at 4L... Do you think we will be on stand a little while longer?
Capt.: Yes, at least another 20-25 minutes. Why?
BBB: Can a very excitable young chap come and have a look at the flight deck?
Capt.: Yes, of course... I think I have some stickers and post cards too, I will dig them out...
BBB: (Whilst looking at the chap, grinning ear to ear) Yes, and something for his little boy would be nice too!
Captain was laughing on the inter phone, and the passenger twigged what I just said and started roaring laughing.
Needless to say, both left with a signed post card and stickers, and both were given a Sky Flyers log book, and with the agreement of the CSD, a First wash bag and a few little odds and end.
Its all about making people happy whenever you can. So many people forget that, for most, flying is a treat. Something they don't do very often, and if someone can make a memory, then why the heck not.
Always ask. Even if you use your young child as a reason to cover up your inner child. ^