With more than twenty arrival stamps from Bangkok International Airport decorating three separate passports, my experience is extensive in the area of what gadgets are needed on a trip to Thailand --and which ones are a waste of precious weight allowances. Since every traveler brings his own personally chosen luxury items (blow dryers, laptops, iPads, DSLRs, GoPros, and on and on and on), I'll discuss how to best connect those devices in your hotel room, Airbnb, hostel, or villa.
First, you'll need Power. Power for when you're on the go and power for when you're back in your room with an electrical source. There are three (to four) items I recommend in this category. First, a Universal Power Adaptor/Converter/Surge Protector and by "universal," I mean the kind you can use again in multiple countries, not just Thailand. I like Fantasi power strip.
This gadget weighs in at 1.3 pounds and is a bit large, but well worth the space it takes up (most of this is in the 6.5 foot power cord). Let's look at some of the reasons this is a great item to take on your next trip if you are traveling with one or more of the following items: computer charger, hair dryer, flat iron, or a camera battery. Not only does this act as a surge protector, protecting you from the many power outages common across South East Asia, but it acts as a power converter allowing you to use your devices from home (120V) in sockets in Thailand (220V). Make special note of this: you cannot use any of the above mentioned items in a socket in Thailand without a power converter. If you try this, you will, without a doubt, create a power outage -- or worse -- in your hotel. The benefit of this particular item of its kind is the long cord. Most hotel rooms in Asia have only two plugs. One in the bathroom (that has loose holes and plugs rarely stay plugged into it) and one in the main room, usually next to the TV over the vanity or desk, or on the floor, on the other side of the room. The longer cord allows you to plug it in and move it about the room. This device has plenty of outlets and plugs for all of your devices, and your traveling companion's too (so only one power Adaptor of this kind is needed for two travelers). It has a three pronged plug so you will need a three to two prong adaptor, available at any hardware store for a coupe of bucks because some outlets in Thailand allow for a three prong plug and others take a two prong plug (yes, Thailand has different types of outlets, sometimes even in the same hotel room)!
The next item I recommend would be for the second traveler in the above scenario to pack is this worldwide travel adaptor. This small, cube shaped Adaptor works well in hotel bathrooms as a phone and iPad charger or for travelers not carrying 110V items. It plugs directly into the wall, so this needs to be considered (you will have to leave it in the wall and not be able to use it while charging).
The final item (or two) is a reliable Power Bank, or two; a multi-charge, larger one and (optional) a smaller, one-two charge unit for day use. Personally, I take two. The larger one for travel days when I may need to recharge a phone twice and boost a fading iPad charge. The smaller is taken on my day to day excursions or to the pool. Rarely do I find bringing both excessive. My iPhone 7plus drains quickly when I am on the road, with use as a camera, for GPS and directions, as an eReader, for Google Translate, and for currency conversion to name a few and having to boost my charge is almost always necessary at least once a day. The multi-use unit I like is this power device and the smaller bank I carry is this portable travel charger by Jackery.
Another option instead of a smaller portable charger is a 3-in-1 Luggage Scale, Charger, Flashlight for around $20 3-in-one Scale, Charger, Flashlight.
Keeping your gear charged can be tricky if you aren't prepared. For example, many hotels in Thailand require you to insert a key into a slot just inside the doorway when entering your hotel room. Without a key in this slot, your power won't go on and often the power outlets don't work either. The trick is to charge up often whenever you can, and always recharge your power banks at night so they are always fully charged in case you don't have frequent access to electric outlets (or in the case of common tropical storms and other causes of power outages). We can become prisoners to our gadgets so let's remember to be flexible with our plans and expectations, the latter of which are better left in our suitcase, or better yet, at home.