So you're planning to start over to play with your wife. Good choice would be classes that complement each other (healer+dps ,tank+healer - makes grouping for instances piece of cake ) but you can choose any classes,doesn't really matter.
2nd class I rolled after lock was druid, because it's total opposite,you can heal,tank and dps. But you got zillion binds with them druids ^^.
Maybe try few classes for few lvls ,see how you you feel them (tho druids are quite boring till you get lv20 and cat form).
Priests are pita at start ,but gets better with higher lvl.
1-60 lvling is quite fast,maybe you could show your wife how to play,teach her some things,after week-two she might get to 60 so you can get back to your lock.