1. The Toilets.
Yes, I’m starting here! If you like to pee as much as I do, buses are not for you. While most buses have a small toilet, it’s usually something resembling a horror scene from Candy Man (kudos if you get the reference). There is no small water basin to wash your hands. Just one that hasn’t worked in years. There is no toilet paper. No hand sanitizer. No flush. And, if it’s anything like the last 2 I’ve been on – no lock on the door and no light! So picture it, my friends, you’re hovering over a nasty toilet seat with your iPhone flashlight app in hand, all while holding the door shut on a moving bus and trying not to inhale… Like I said, horror scene!
2. The Thieves

Anytime you board the bus, you are asked to store your larger bag in the cabin below the bus. Important: DO NOT LEAVE ANYTHING VALUABLE IN THIS BAG. It will not make it to the other end with you ☹. Some travel agencies are nice enough to warn you of this risk before you leave, others are not. I have heard many a story of travelers having their electronics stolen or even small amounts of foreign currency left lingering in their bag stolen. So just be sure you have a proper carry on bag to house your most valuable items. (I recommend a waist pouch that fits snug under clothes for your passport and credit card, too.)
3. The Costs
If you have to take the bus, buy your ticket directly from the bus station whenever possible. If you are going to a place that requires 2 buses (for example, going from Chiang Mai to Koh Tao requires a stop in Bangkok), then DO NOT purchases both tickets together. You’ll likely be gauged (Um, like I was :P). A bus ticket to Bangkok from Chaing Mai should cost about 600 Bhat. From Bangkok to Koh Tao or Koh Lanta is 750. Often when you buy the 2 tickets together, the travel agent adds a few hundred bhat or so (6-12 USD) for themselves. Especially if they can tell you it’s because of the busy holiday season.
Whenever possible, at least ask to more than one travel agent and ask a local person that you can trust what the bus fare (or ferry fare) should be. (Note: If your hostel or guesthouse offers travel, they will want you to book through them but they will likely mark up the prices, too. Don’t get too attached to smiling faces that feed you breakfast!!)
4. The Dodgy Restaurants
The buses will stop so you can eat. And they will stop somewhere that you would never, in 100 reincarnations, ever consider eating at were you in your car looking to pull over. It will often be a grimy joint that relies solely on these buses stopping to make any money. The food will look like it’s been sitting for years. If you’re really lucky, it will be a small market, but the choices will be limited to a few spicy or deep fried dishes. It’s a good idea to pack a meal before you travel if you have a certain diet or have a sensitive stomach.
5. Sheep Syndrome
You will notice there are no Thai people on your bus. If you see one, they are likely family of the bus driver and the front seat will be reserved for them. Everyone on your bus is a tourist. A number. And you will be herded around as such, often in an unorganized and unfriendly manner. You won’t be politely informed on bus changes, stops, or arrival times. Just abrupt shouts when it’s time to get off the bus. Folks, don’t get me wrong, Thai people are friendly, but these are my experiences on Thai buses. Please comment if you have a happier experience to share!

Trains & Planes
I like trains in Thailand because the price is fixed and both Thais and tourists use them. You will see more tourists, though. I asked a Thai friend why that is and she told me, “Thais always take the fastest option. Time is money.” Makes sense.
The trains have better toilets and even water in the sink to wash your hands ☺. Also, you can get a pretty comfortable sleeper train and feel rested when you arrive at your destination. Just put your backpack right in the bed behind the little curtain with you. Hug it. Throw a leg over it if it seems safer to you! But anyway you slice it, it’s more assuring than a bag under the bus. You can order food on the train, too. It’s not the best, but it isn’t bad.
Planes are, of course, the fast and convenient option, but for many locations you will have to take a smaller bus or ferry on to your final destination. If you want to go from the north of Thailand to the south, you can fly from Chiang Mai to Phuket on the west or Samui on the east. Samui generally costs more, but given that it takes 2 full days almost to get from Chiang Mai to Koh Tao, Koh Phangan or other popular islands, you might just find that extra $50 or so USD is well spent!
Happy Travels.