I felt like livening up this thread!
This is probably too late to help, but I felt like adding a few for the future. Brussels is not such a great shopping city. Main locations are:
- Rue Neuve: Personally, I hate it. It's just the one big pedestrian street where all the regular shops (Zara, H&M, Mango) can be found. However, the funkiest H&M is here. Just don't go on the weekend!
- Avenue Louise: Many upscale 'established' designer boutiques. Some funkier ones, like Louise 54, carry a mix of Marni, Marc Jacobs, Chloe, Balenciaga... Also there's Senteurs d'Ailleurs, a really great non-conventional perfume shop with brands like l'Artisan Parfumeur, Serge Lutens, Yux...
- Boulevard de Waterloo: regular designer shops, Dior, Chanel, Gucci, Sonia Rykiel, Delvaux, La Perla etc. If you turn left at the intersection with Chaussee d'Ixelles, you wind up on a street (forgotten the name) that has a few more interesting designer shops, such as a Kenzo
- Chaussee d'Ixelles: This isn't really such a great shopping street but it has a nicer atmosphere than Rue Neuve and carries shops like Mango, H&M, the Body Shop - I prefer these outlets to the ones on Rue Neuve
- Like faust said, Rue Antoine Dansaert is the most interesting shopping street in all of Brussels! Stijl is probably the most worthwhile, since it carries beautiful items from Belgian designers. The vintage shop next to it, Idiz Bar, is also a must-see though. The street has many other interesting shops besides that (Rouge, Marithe+Francois Girbaud - and if you walk farther there's a Comme des Garcons/Yamamoto)
- The Marolles neighborhood has most of the shops open on Sundays. There are mainly furniture stores, with a few vintage places thrown in. It's a slightly alternative neighborhood; much of the furniture will be empire, 60s retro, colonial or asian. There's also a very cool natural skincare products shop on Rue Haute, I think. Last time I was there, the saleswoman was discussing the merits of meditational Tibetan bowls with a customer
Hope this helps anyone who's visiting Brussels in the future
!