It's been my experience that most players have a certain stereotype that they gravitate towards. For some, it's the ability to sling spells. Others enjoy the hot stink of an opponents breath in their face as they wade into melee. Still others prefer to stand at the back and rain death upon their foes with bows and guns. There's no right or wrong choice so longs as you're enjoying yourself.
It's a good thing to change it up a bit on occasion too. It gives you chance to see what you're missing and even remind yourself as to why you might not care for one class or group of classes. And don't sweat it if you start a character and aren't digging it. You can always put her on the shelf for a while and dust her off now and again down the road.
Jonathan's got a good suggestion of running mock combats. If you've played some higher level scenarios, you might try replaying them without credit to get a more complete experience as well.
