[Draggor]

A single level of two of another class is good because it gives you character versatility. You get more value out of adding a whole new class than adding a level to an existing class. My character is a level 18fighter/2rogue. I added just enough to rogue to put a few levels into locks/traps and use magic device. It hasn't really weakened my fighter any, I still have four attacks and only lost one feat, but I gained sneak attack, evasion, lots of skill points and the ability to use mage and cleric scrolls with use magic device. Fighter is a good option for a second class for any character. You gain 1d10 hp, all the weapon and armour proficincies and a bonus feat. And unlike 2nd ed you can easily add a second class and it costs the same experience to become a cleric10/wizard10 as a cleric20