Baldur's Gate 2 - Waukeen's Promenade Side Quests
This zone has a bunch of buildings which are used in quests and shops that will sell a wide variety of different items. At the northern end of Waukeen's Promenade you'll find one of the only spell shops in Athkatla run by Galoomp the Bookkeeper. The other store worth mentioning is the Adventurer Mart which has numerous vendors that sell some of the best items in the game.
In Waukeen's Promenade you'll only find a single dungeon, the Circus Tent, which is also where you'll meet a new companion by the name of Aerie.
Spells: Galoomp the Bookkeeper is found in the northern end of this zone, there is a map marker named "Spell Store" at the top of the map which is where you can find Galoomp. He sells a wide variety of Wizard spells for spell levels 1 - 5; arguably this vendor has the most spells of any spell vendor in town.
Adventurer's Mart:
Circus: