This thread has been repeated many times. The TSA doesn't seem to care about radios. They do get excited once in a while about coax and wires, but I check those through. On the other hand, it's worth pointing out that the FAA doesn't want you to operate radios on the plane for either receiving or transmitting. If you fly frequently get a Known Traveler Number and/or a Global Entry Card. I'm usually through check points in a minute or two even at LAX. Check with ARRL for overseas operating. Some countries I've visited, like Ireland, have no formalities. Just bring a copy or your license. For Japan you need to allow a minimum of 6 weeks to get a permit. Then there are countries where you don't want to bring a radio PERIOD. Check before you travel. Scanners may be illegal in some countries and useless in others due to encryption and cellular like communications systems. Ireland uses the 66-88Mhz band for fire and TETRA for police. Fire may have switched too.
Enjoy the scenery and take pictures. You can do radio at home. Be sure to get an overseas calling plan for your phone. Watch out for pick pockets. I had three or four people try for my wallet in the Metro in Paris in one evening.