I travel a fair deal for work
(both international and domestic
). If you know where you're going to stay
(or if you book it yourself
), give the hotel a call and ask them about their own fitness facilities or if they are offering discounted rates at facilities in the area. You'll be surprised how many hotels can arrange excellent faciltities for a very nominal fee.
If you're member in the local Y, try calling the Y in the town your visiting ask about their visitors rules. Quite often there's a membership exchange program, and all you need is the membership card from your Y
(there might be a small fee as well
).
If you are meeting someone local, why not ask them for suggestions.
As you pointed out, running is very often doable, although I've had time where not even that's an option... could be unsafe areas
(try running in the industrial areas of Shanghai for example! unsafe is not even close to describing it...
), long days and lack of daylight, etc.
Worst case scenario, develop a strength and flexibility program that you can do in your hotel room. You'll get something in even if you can't go running.
Most important is not to stress about it. Trust that your training has been good and use the travel weeks to recover
(also try to think about your diet on the road, which can be a challenge, especially if you're entertaining as well
)