From a high level it's easy to look at a device or a system and say "All these options are making this really hard. This thing should do less." But less is just a direction, and it's only useful to go that way until you can't do something you need to do.

The iPad isn't a success because it just does less than everything else. It succeeds because it does what it's supposed to do incredibly well. Users have certain expectations when they pick up an iPad and the iPad generally lets the user do what they expect and is intuitive in the process.

In the case of travel websites it often seems that no one has taken the time to consider what users will actually do on the site, instead just lazily giving users every possible option. For example, if a booking site has found me a $300 nonstop ticket it's probably not necessary to show me the 3-stop, $1700 option. Yet they all do because nobody has taken the time to filter down the results to the practical options (the user could create a filter, but that's just another option to deal with). I would much rather see just the 5 flight options that I'm likely to buy instead of 30 options with 5 potential winners buried in there somewhere.

If you're building a tool, the user will have to give some input. The key is to give the user what they want with the minimum possible amount of information.