Yes. You have to book the higher fare classes and often it's a lot more money. Sometimes it's not so much more and sometimes the lower fare classes are not available anyway.

The problem then comes that very often, having bought the higher fare class, no upgrade space is available and you've wasted your money. You can get around this if you are lucky enough to see R space available when you book - but, IME, UA then prices the W class substantially higher on that particular flight.