Online travel sites can tell prospective travelers which airlines have the cheapest seats, which hotels have the best views and which attractions are "must sees." However, investing in these Internet bookers' stocks may not always get your portfolio to its desired destination.

So far this year, investors have been on a whirlwind of a trip. While shares of some of these virtual travel agencies rocketed higher, others seemed stuck in the doldrums. Take a look at Priceline.com and Expedia. Priceline.com has gained plenty of altitude this year, climbing an awe-inspiring 79% to a recent $40. Meanwhile, shares of the jumbo jet of online travel, Expedia, have been grounded in 2006, falling 24% to around $18.

The disparity is as vast as whether you sit in first class or coach. Each company has its own strengths and weaknesses, and it may be surprising to see where each takes shareholders next year. Here are some clues that should help investors pack their portfolios accordingly.

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