Less is more, so for DSLR shooters look for a wide zoom lens that covers at least 28-135. There is no perfect lens for all situations but keep in mind you will be carrying your gear the entire trip, so my suggestion is to take no more then two lenses at most.
Pick the right bag. I’m a bag junkie, having four dedicated photography bags but always looking for another. Your travel destination will help you choose what kind of bag you want, but here’s a quick primer from my experience. Photo backpacks are great for transporting gear from point A to B but are terrible to work out of. Sling bags are easier to get gear in and out of but are usually smaller. I’ve never found hip bags comfortable to wear but some people swear they are the best to work out of. The last type of bag is the overly popular messenger bag. This is my preferred type of bag to work out of, however it took me a while to find one I really liked. When I travel, I put all my gear in a photo backpack and pack my photo messenger bag in my checked luggage. When I get to the location, I’ll put my gear into the messenger bag to work out of.
Leave the kitchen sink at home. Sure, a small, packable tripod is OK to take if it fits in your luggage and you plan on getting sunrise / sunset photos and need the stability, but you probably don’t need everything else in your camera arsenal. Really think about where you will be going, what you will be photographing and how much stuff you want to lug around.
Batteries, chargers and power converters are essentials! Fully charge all your batteries before going and make sure they are in your camera and other devices. Some airport security will ask you to turn on your camera or laptop to ensure it’s a real, working device. If you are going to another country they may not have readily available AA batteries for your flash, take spares and/or a charger. Likewise, look to see what power options are available where you are going and if you need an inverter or converter for your gear. I always suggest taking a small power strip with surge protector as an added layer of protection if you are uncertain of voltage where you are charging your devices.
Take a few microfiber cloths to keep your lenses and gear clean. Dirt and debris can ruin equipment, so can getting caught in the rain for even a few minutes. These cheap, very handy microfiber cloths will ensure you get clear and sharp photos and your gear is in tip-top shape.
Take lots of memory cards! Memory cards are cheap compared to even a few years ago, take double the amount you think you could use.
The details are what make trips memorable. For example, Miami is well known for the art deco hotels, but it’s the small details about them that make the difference.
Get up before the sun rises one morning. Scout a location the day or two before and plan to be there before the sun rises. Morning light with the sun breaking the horizon can be one of the most beautiful things for any city or landscape shot.
Be courteous of the locals. Just because you are in a different city or country doesn’t mean everyone immediately wants to have their photo taken and pose for you. When you shoot people, always be courteous and show them respect. If you are in a country where you don’t
speak the language of the locals, show them the photo on the LCD of your camera so they understand what it is you are doing.
Have fun! Enjoy the vacation. Don’t spend the entire time looking through the view finder and post processing photos at night in your hotel room. Don’t forget to soak up as much of your travel adventure with your own eyes as possible.