We've checked our carseats (first a Graco Snugride, then a Britax Roundabout) a few times and have never had a problem. Just get one of those $30-40 backpack carriers for the carseat and check it. The backpack carrier makes it easier to get the carseat from baggage claim to your rental car or whatever, too. I wouldn't recommend checking the carseat "bare" and plastic bags just don't give enough protection (we had a plastic bag rip off one time and got a little stain on our car seat--that's when we bought our backpack carrier). But an inexpensive canvas carrier will give it pretty good protection from being stained or ripped.

I know the purists out there are concerned that by letting it get banged around by baggage handlers you might risk compromising the structural integrity of the carseat. But I think there are much bigger things to worry about in this world than whether the plastic structure of my car seat might be slightly weakened by being tossed around. The odds seem extremely low of the seat being critically weakened in an invisible way AND you later being in a car accident where that weakness causes your kid to get hurt. I think there's a much greater chance of your kid getting hurt because you were trying to lug the carseat and all your other stuff and couldn't grab him when he went to run out in front of a speeding luggage cart in the airport or something.

If you're still not comfortable, however, just order a Scenera, have it shipped to your destination, then donate it to Goodwill or something when you're done using it.