Also, you need to make sure that your transformer/inverter has enough wattage to support everything you plug in.

Many of the smaller ones rate between 60-100W in which case if you plug several things into a power strip it will overload it. Tranformers generally are more heavy duty than inverters so they can handle more but they are expensive and heavy.

Many (but not all) electronic devices such as laptops, cell phone chargers, etc. will have a power supply that can run on currents worldwide, you just need to a plug adapter (reason: it's cheaper to make one universal power supply that works across a range of voltages than to make a bunch of different ones for each market).

What you want to see on your power supply/charger is something like this: "Input 110-240 V (volts), 50-60Hz (Hertz)". If you see this, you can safely plug it in just about anywhere in the world, as long as you have a plug adapter.

Examples of devices that I travel with which can run on worldwide are my bose headphones battery charger, my cell phone charger, my laptop, and my bluetooth headset charger.

And here is another trick, the most common item left behind in a hotel room is a cell phone charger. Every hotel has boxes and boxes of them in lost and found. Chances are good that if you ask lost and found in your hotel they will have a local plug cell phone charger that will work with your phone. Most of the time they will even let you keep it.

In my travel experience with my wife the biggest thing is usually a curling iron. You can get an iron or hairdryer at any *wood hotel. We recently found a travel curling iron that ran on Butane like a lighter. She was so happy.