I have 2 Gold World Airmiles Mastercards, one for business expenses, and one for personal. I buy a shit-tonne of gas for work, among other things, and I easily get enough miles a year for a trip to Europe (or up to 10 domestic return flights) for the annual fee of $129/card (the business card is a write-off for me).
Completely worth it for me. I don't fly a lot for work though, so something with actual airline perks, wouldn't give me much benefit. The airmiles I collect, can be used on any participating airline, through the airmiles site. My husband and I went to Hawaii 2 years ago, (along with a few domestic flights), and I'm heading to Seattle with a friend next month, and we still have 10,000+ miles left over for more travel this summer.
It all depends on your spending habits. This card has some sort of 18% interest rate, but I've never paid a penny in interest to them. I have a friend who flies internationally a few times a month for work, and she is a platinum on a few different airlines, and really enjoys the private lounges, and the upgrades on all her personal travel.