That trio will work just fine if that's what you and the wife want to play. Any Tank/Healer duo with any 3rd box will do ok. Any Enchanter with any other 2 classes will do ok. Folks typically avoid SK/Necro because their skills overlap so much, but it will definitely work. I consider playing 3 toons an awkward number of characters. When 2 boxing, you want both toons to cover as many roles as possible, which is why SK/Sham is so powerful (tank, FD, snare, dots, slows, heals, buffs). When you play 4 toons you want toons that are the best at what they do (for example, tank, cleric, enchanter, wizard). With 3 boxes you are kinda in between, and if you are playing 3 toons at once, it won't be long before you want to add a 4th and will be wishing you had Enchanter/Cleric instead of Shaman. I know I wish I could switch from SK/Sham/Bard/Mage to SK/Cleric/Enchant/Wizard if I could start all over, but I grew my 4 box organically from an SK/Sham duo that added the Mage for DPS, and then the Bard for Lull/CC/Mana.