I like to wear lots of different watches but when traveling it's best to only bring 2 or 3. So how can you pick which pieces from your collection to bring? Here's what works for me.
When I pack for travel, I typically pack a pair of sneakers for high-step-count touristy days, sandals for the pool or beach, and a pair of low heels or dressy flats for going out. Watches work basically the same way!
Maybe this goes without saying but, if you're traveling overseas or several time zones away, a watch with a GMT or world time complication will come in handy.
Don't bring anything you'd be heartbroken about if it were lost or stolen, be it for sentimental or financial reasons. What this means will depend on your financial situation and the relationship you have with your watches. For me, this means I leave my grandfather's Seamaster & my luxury pieces at home, and roughly cap the value of anything I bring to about $300 or less.
If you have some luxury piece that you absolutely love, are dying to bring, but can't bring yourself to risk it, consider a clomage of it for travel. This is just like how you pack costume jewelry instead of your real jewelry. For instance, I have a Seestern GS homage that's surprisingly decent & feels a lot like a real Grand Seiko (see this review). It makes a great dressy option for travel, and is at least an order of magnitude less expensive than a real 44GS. Another example is the Seiko SUP250, an inexpensive Tank clone that looks great and won't break the bank.
For a recent trip I took to London and Greece, I took three watches: