There are other sites that sell things for Bitcoins that are not drugs. But there aren't that many of them.
You have to get the banks to support Bitcoin so you can exchange from Bitcoin and back and that hasn't happened on a large scale yet.
When I went to buy Bitcoin I saw a lot of Russian based sites, and not sure I could trust my bank account info with them as they might be run by the Russian mafia for money laundering.
But there's always another market. And there always will be.
It's miles ahead of any other payment system I know, including cash (because you don't have to be in proximity of the recipient).
Who exactly are you buying plane tickets from?
The last time I bought tickets, it took less than a minute to pay with a credit card. I spent more time searching for a flight with wifi.
Bitcoin transactions can take up to 10-15 minutes just to complete.
Funny, because the times I have used Bitcoin it has taken a solid hour, or more, for the payment to 'complete' due to the confirmations required. This for pathetic, tiny payments (like $10 or so), When using a card for airline tickets, for thousands, it takes seconds.