My wife and I (and our twin 8 week old DSs) are planning (well, we are, they're not) on going to South Africa in December to visit some family when the kids will be about 6 months old. No one there has any cots there, so we were wondering...
Would you take a travel cot? Buy something cheap when you're there? Let them sleep in your bed? Something else? I mean, a travel cot is a bit of a misnomer. I presume its called a 'travel' cot because it collapses and has wheels, but its still heavy beyond belief!
Also, what would they sleep in on the plane? Do plane companies provide anything?
Airtravel : a bassinet is a little cot that is attached to the bulkheads (front wall separations) on planes. They are limited in number so you need to make sure you prebook with the airline when you book your seats. You can take a look on the airline websites in the section 'travelling with children' and they will indicate how to book them and what are the limitations in weight and size.
For the travel cots, we had one of those huge things for DD1 which are really only suitable when you can shove them into a car boot - not really transportable. If you can't hire or borrow one locally, then there are now more alternatives (as we discovered with DD2). We live abroad and travel often and have bought a pop up travel cot. They look like little tents. Amazing. Total weight 2.5Kg, fits into suitcases and DD2 has had no trouble sleeping in it from day 1. Takes about 2 minutes to set up. You can take a look on websites such as Amazon, where they have listings of different brands that make these things. We have a samsonite version but there are several brands/options available and I certainly wouldn't be without it. We take it everywhere for afternoon naps when out and about.
The bassinet is the fold-down baby bed in front of the bulk-head seats. Just tell the airline you are flying with twins and will need two of them. Then call the airline every day for the week before you leave and badger them to make sure you get them. Then check-in the second that check-in opens and get to the airport early to avoid missing out.
We also used to hire cots etc, lugging them won't be an option given weight restrictions.
We have one of the tent-like travel cots like shanghaied. This is the one we have (although we didn't buy it from this website): http://www.pushchairs.co.uk/acatalog/nomad_travel_bed.html
It is great, and is longer than the normal travel cots so can be used for longer. Our DD is 2.3 and she still uses it when we go away. It fits really easily into a suitcase. The self-inflating mattress is also much more comfy than the very hard bases in normal travel cots.
If you're likely to travel there a few times, it may be simplest to get someone from your family there to buy a travel cot for you (before you get there), and you reimburse them for it. And then ask them to store it between trips.