OK - I'm going to "jump" in and remember the glory days as well...
I was lucky enough to visit the flight deck on half a dozen occasions in total, including three approaches and landings (B737 (-200 ???) into Amsterdam, RJ100 into Gatwick, B747-200 into Orlando). Every time the flight crew were great, explaining things clearly and obviously enjoying the break in the monotony of 3-sectors-a-day flying. At the time I was a student pilot (my PPL was being minted on "the day the doors closed") and the crew were always keen to ask where I was learning, how was I finding it, what sort of aeroplane was I flying etc etc etc.
Since the horrible events of last year, sadly, flight deck visits have been off the agenda. I have been lucky enough to visit "the office" twice since then, but only while on the ground and only during delayed departures. The crew are very busy before the flight if they're trying to meet their planned slot, and also after landing if they're doing a "normal" turnaround, so much so that I have the courtesy not to ask. Sadly the rules that are currently in force mean that I have to leave just before engine-start, but I still find the crew seem pleased to have someone to talk to for a change!
I will second the opinion about ITVV's videos and DVDs - it's not the same as being there, but given the current regulations it is (in my opinion) the most cost-effective option open at the present time.
One thing I would love to do is to visit a full-motion simulator, although sadly the commercial opportunities available are too pricey - I'd rather spend that sort of money on flying myself in a Katana! I would love to sit in on an ATPL sim-check, however I suspect most ATPL holders find these quite stressful enough without another person sitting in the sim asking stupid questions!
Sadly (for all concerned) jump-seat rides are very, very unlikely in the present climate, and the situation is unlikey to change in the foreseeable future
Cheers,
MD.