The Antwerpen Hilton is the best hotel in town with one of the best locations of any hotel in Europe. It's right on the large Groenplatz square next to an enormous Cathedral. The whole neighborhood is alive with literally hundreds of shops, cafe's and restaurants. They have an underground parking garage.
I think rack rates are around 9000 BEF, but if you can get a corporate rate it's about 5000 francs. It's well worth the extra money since most of the other hotels in the area aren't very good. Plus, Hilton has Double Dip points right now.
If you are driving from Brussels, head for Antwerpen Centrum and follow the Ring to the right. You'll get to the water which you follow till you see the bridge and then turn left down the tiny stone streets til you see the Hilton or the Cathedral.