Warrior and Ranger are solid first choices to explore the lands (Good melee offense + defense = better for PVE). I'd also recommend Warmaster and a neutral alignment so you can receive help from everywhere. Tribunal... sure you get an extra pet (which doesn't help in PVE btw), but now you're obligated to hunt criminals. Knight isn't a bad choice for the support, however they are somewhat full and have some pretty nasty enemies too. But in the end, you should pick what you are drawn to. At the end of the day, its about creating a char and a path you love because that is where you will have the most enjoyment.
Ogre is always among the top choices for their high strength, high hp pool, and fast regeneration speed. Certainly you can try other races like feral, stone giant, slith, duergar/dwarf, etc. But for raw benefits overall, ogre is a good pick even with the magic vulnerability. Not to deter you from the other choices though. I've seen some strong non-ogres too.
Berserkers and monks are just plain fun classes to play. High offensive damage capabilities makes for an enjoyable time PVE (as long as you aren't the tank). If your son is just getting his feet wet, i'd say have at it and enjoy yourself. In the PvP realm, however, they require a lot more finesse and skill to succeed with. Usually you will be fighting an uphill battle against classes like warriors that WILL outmelee you. But at the same time, you get some unique skills which can be deadly in the right situations. Hope this information helped.