I would suggest going with the quest route to catch the war up. Grab the QuestHelper and Cartographer addons and you will blaze through the quests then hit the dungeons if/when you run out of quests. Having the higher level around to help with red-con quests makes things smooth sailing.

Once they (druid/war) are symc'd up you can keep questing all the way through, or dabble in some instance grinding as well (for that pair i would go quest all the way though).