I booked my flight and chose a seat 6 weeks before I went. I didn't do an online check in and lo and behold, my seat was taken by someone else. I actually got a very nice seat in the area that is generally reserved for families with kids, near the stewards kitchen. I will in future check in online as I assume that your seat can be taken unless you have actually checked in.

Always check in online with Emirates, only carry hand luggage so its straight through departures, did the same with Qatar but when it came to boarding they said, you cannot use an online printed boarding pass you have to have one of ours, so everyone who had a online pass had to wait until last then wait for them to print new passes. Waste of time really.

A couple more:

- On TG domestic flights, you are unable to select a seat at the time of booking, but you can select a seat with online check-in, commencing 24 hours prior to departure.

- Many airlines consider the order of check-in when doing operational upgrades. That is, if you have a lower check-in number, your opportunity for an upgrade may come up earlier than those who checked in later.

Last time I was at Suvranabhumi wnated to do bag drop but the line for that was longer than the checkin line.

Bag drop line will generally move faster.