Waukeen's Promenade Overview - Baldur's Gate 2
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 a wide variety of really good magical items and some high level spell scrolls.
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. There is one more fight worth pointing out in this area which takes place inside the Den of the Seven Vales.
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: Adventurer's Mart is a shop with multiple vendors that all have a variety of great loot for sale. Ribald has the most items for sale, there's definitely going to be some you can use early on. Deidre in the back has the most unique items, she has stuff like Shield of Balduran, Sword of Balduran, Dak'kon's Zerth Blade +2 and most importantly Robe of Vecna. I'd recommend speaking with Lady Yuth inside of here too as she has quite a wide range of spells for sale as well as a Scroll Case.
Circus: This is the only dungeon in Waukeen's Promenade and it's involved in the Investigate The Circus Tent Side Quest. You should do this dungeon early on in the game since it's pretty much designed for low level players. Inside this dungeon you'll meet Aerie who is an elf who has lost her wings and a potential companion & romantic interest in BG2.
Den of the Seven Vales: On the 2nd floor of this inn you'll find a group of very angry adventurers that will attack you if you provoke them even slightly. This will be a very hard fight early on during the game but will net you 28,000 EXP and a bunch of magical items including Sandthief's Ring, Cursed Berserking Sword +3, Whispers of Silence (Cloak), various weapons and a Wand.
Jayes: Night time vendor in the eastern portion of Waukeen's Promenade. This vendor actually sells some pretty decent magical weapons and has a couple of Wizard spells which you can't get from the other vendors in this area, I would recommend you check this guy out.