You don’t want to pick a genre that won’t give you many options. Trying to photograph the milky way in New York isn’t going to happen. Neither is photographing architecture in Yosemite. Come up with something that will give you a lot of material to work with and that you will actually enjoy.
Travel photography conjures images of epic landscapes or cityscapes. You really are only limited by your imagination. Try making the local people your theme with portraiture. Spend your days practicing street photography if you’re visiting an urban location. Maybe even try your hand at wildlife photography if there’s any around.
So, you’ve picked a genre. What are you going to point your camera at? It’s time to spend some time thinking about the subject of your theme. Again, it may be an easy decision. What’s unique about the location you’re visiting? What’s it known for?