The first time I flew Air Asia and didn't know about the 15 kg limit, I was over the weight, so I said, "Here, I'll carry on that one(bigger bag), and check this one(smaller bag), and tried to switch them, but they grabbed the bigger one away before I could get it, and weighed the carry-on bag which I had set one the scale when I tried to switch them. Then, against my protests, they added in the weight of the carry-on and charged me for the whole lot of it.
I've been very careful, since then, stowing bags at a hotel with storage once, and another time with a friend, when I had to fly Air Asia to get to Cambodia. Even then, I just barely made the limit, by putting the heavier stuff into the carry-on bag, and strapping my computer bag over my shoulder, and with extra stuff jammed into the computer bag, as well. Most airlines won't count a computer bag as an extra carry-on bag.
Now I fly Orient Thai whenever possible. Their limit is higher, 20 kg, and they didn't bat any eye when I was 2 kg over weight. No extra charge, didn't say anything. They also did not say anything about the fact that I carried on my suitcase, which probably weighed at least 10 kg, maybe 15. Plus the computer bag!!
Nok Air allows an upgrade to 30 kg and premium service/seat for a reasonable fee, but it was a big hassle to book online or over the phone with them with a US credit card. The premium service is called NOK PLUS: "In addition to the larger seats, Nok Plus passengers will enjoy the privilege of being able to change their travel date without a change fee*. Also Nok Plus passengers will receive a free snack on board, newspapers, and benefit from a total of 30kg baggage allowance as opposed to 15kg in economy class."
Orient Thai also has a special discount deal currently available. When you buy a ticket, you get a coupon for a 500 baht discount the next time you buy a ticket for yourself. I like Orient Thai!
