Wearing tight fitting clothes on an airplane can not only be uncomfortable, it can also be dangerous to your health! Deep Vein Thrombosis (DVT) is a potentially life-threatening condition where blood clots form (usually in the legs) due to a lack of circulation -- something that sitting in a cramped seat during a long flight can lead to. Wearing tight-fitting clothing restricts your circulation further, putting you at an even greater risk for DVT. Leave the tight clothes in your luggage and make sure to get up and walk around a couple of times during the flight to get your circulation flowing.
While flying, you run the risk of having drinks and food spilled on you by clumsy passengers and crew. Dark colored clothing hides stains better than light clothing will, and has the added benefit of camouflaging wrinkles a little better. Even if you make it through your flight unstained, think of what will happen if the airline loses your luggage (which happens a bit more frequently than they would lead you to believe). You may wind up having to wear the same outfit for a few days, and dark clothing is typically more durable than lighter garments.
Comfy footwear should always be on your packing list when traveling, especially when you will be flying. The changes in pressure in the cabin of an airplane can cause your feet to swell up, so having soft shoes you can slip out of if necessary is a big plus. Also, having easily removed footwear will help you get through security checkpoints faster -- many airports now force you to remove your shoes while passing through security, and the less buckles and laces to deal with, the better!
