I guess it depends on how big a dio you want to do, and what country you want to set the scene in.
The tenement is fantastically detailed and a reasonable size, but very, well, German. Fine for it's intended placement, but might look a little odd in a Normandy setting.
Conte's range of formtech buildings are very good if you can get hold of them and work well with 1/30, even though designed for 1/32.
Hobby Bunker do a nice range of their own formtech buildings which would go well with a number of European settings.
You've already mentioned BAR, there's also JG miniatures who do a building line.
Nick Nasta (forum member here) makes his own and sells through George (Warrior) at Minutemen Toy Soldiers. You could do a lot worse than have a look through Georges site:
www.mmtoysoldiers.com
George is the terrain king of the hobby and has got a ridiculous amount of pieces for sale.
Simon