Project folder or,not really GTD a "dated items box" or "take out box".
When I travel, I usually have the trip listed as an active project and hence it has a folder with a name and a date such as Tuscon 2009: JE (me) and name of anyone who is traveling with me and purpose, such as vacation, furniture mart, pick up puppy, whatever. I would have that folder in my active drawer, probably until I packed my bag or if I had the bag out a few days in advance, I might put it in it. I would probably also have in the folder maps, brochures, addresses, maybe even some postage stamps, and if I was focused enough, a photocopy of my credit cards and anything else I can fit on the flat bed copier, like my license, and the tickets themselves or paper itinerary/e-ticket. and you are disciplined enough to use it
I also have a checklist for the trip in my palm and a copy printed out in the folder, as I may have physically marked on it things like the day I requested the mail be held.
If the trip was routine with no additional papers going with me, I would put the tickets in my wallet if it was within a week or ten days but if the trip was far off in future they would go in my mini-holder that is one little hanging box for all things with a date that are singletons such as theatre tickets, opera schedule, invitations I have accepted, movie passes, dated coupons. There are just not enough of these to justify the tickler and some of them have more than one date as an option, so for example, the opera tickets are applicable to one of three performances, up to a certain date. I have the date for that on my calendar. This only works if there is not a lot of stuff in it and is in the category of "knowing where to look for something".
One other place to put the tickets is in a "take out box", a box or tray for stuff you have to take with you regularly and/or at some definite point. This is an open tray (like an in-box) for outgoing mail, shopping list, parking meter coins, bus tokens, etc. I know someone who puts his keys in this tray when he comes home, along with ID badge for work, next to it is the master bottle of hand sanitizer for refilling the pocket size bottle, and new lip balms and he also leaves his phone to charge there. He gathers his stuff from this tray and checks it when he leaves for anything. Again, this only works if there is not a lot of stuff in it and you do not use it as a catch all.