Zones by level: http://www.wowpedia.org/Zones_by_level

Instances:
Vanilla: http://www.wowpedia.org/World_of_War...ances_by_level
BC: http://www.wowpedia.org/The_Burning_...ances_by_level
Wrath: http://www.wowpedia.org/Wrath_of_the...ances_by_level
Cata: http://www.wowpedia.org/Cataclysm_instances_by_level