I have been on United quite a number of times to Europe. I have never ever sat in anything lower than Business Class. Last time was ZRH-IAD in First Class. By myself. I don't think flying on a Gulfstream G550 would have been much nicer.

Dress nicely (for real, maybe even a tie). Be very polite. And humble. Always works for me.

I'd go with UA or Delta. United has always treated me so well; they are a class act. Delta is a good one to go with as well. American's always treated me well domestically, but I've never been with them internationally. I think you can jumpseat internationally, just not in the cockpit, but they may flat out not let you jumpseat internationally.
With CAL, I've never been in business. I've been on plenty of empty planes and literally gotten the last row, once a middle seat. I am thoroughly grateful for the ride, and the Continental pilots are always class act, it's just funny to see the difference between United and Continental in those regards.
Go on UAL if you can do it easily.

Thank You for the info guys!
I always am thankful for the rides that we recieve and I am always very willing to have a jumpseater on our aircraft!
As far as sitting up front, not a big deal BUT, it is definitely nice after finishing a trip and hustling off to a vacation (trying to snag an extra vacation day out of your schedule!!!).
My experience has been great with Delta Crews. I think I will try United though and change things up ;)
Thanks Again!

For the guys that got the upgrades, were you in uniform? Or just after getting on the plane asked to talk to that captain to thank for the ride, and they upgrade you on their own?

Also, how about checking baggage when you are jumpseating on a different carrier intl or domestic? You go about it the same way as if you were on your own carrier?

I am also interested about whether or not you guys were in uniform ...
My experience checking bags with DL was going to the counter and listing for the jumpseat there. Then checking a bag with the agent. There were no fees associated with the checked bags.

I think the bag checking rules change July 1st for DAL, but I'm sure about employees. How about getting back from EZE obviously you can't jumpseat so would you get a ZED or something?

Yes, you can ride using the jumpseat privilege, you just can't occupy the cockpit jumpseat.

And make sure you check in for the js at a minimum of 75 minutes prior to departure for TSA requirements

As a frequent international jumpseater I can tell you CAL and DAL are awesome. AA won't let you jumpseat internationally, period. Kinda funny how they can ride on us on the JS but we cant do the same. Don't count on jumpseating back into the US, you can only JS out. Requesting to JS back in will result in a confused foreign gate agent.