Delirium in Brussels has a menu of 2000 beers, not 1000. I was unaware of "MANY small breweries around the city" but you can easily visit the Cantillon brewery (http://www.cantillon.be/br/3_1) near Gare du Midi and the brewing museum in the Grand' Place (entrance price includes a beer at the end of the tour).
See trabel.com/brussel/brussels-cityofbeer.htm which also covers "historic bars" - Delirium is hardly historic, but the bar of the Toone puppet theatre off petite rue des Bouchers would qualify. It would be difficult to get out to any of the abbeys (whose buildings are often less historic than you might expect) without driving, but they have abbey beers at e.g. Beermania, www.beermania.be.
While there are a FEW other breweries in Brussels, such as Belle-Vue, you can usually only visit on certain days and with a bigger group than 7, see …angloinfo.com/af/506/brussels-vineyards-and…