There are always spotters at BRU - where depends on the landing runway but seek and ye shall find.
Seriously, try near the water tower, or walk along the fence to the "prison" if they are landing 25L, near the cemetery in Zaventem or on the dirt mound if they are on 02. If you are not mobile then "Wingtips" or car park roof will often bring you a companion.
Until now I haven't planned to go spotting this weekend. I'll have some work to do for university . But if there's something special coming (also big ones - like B777) you can count me in.
Would like to go to BRU too with the good weather but will be tomorrow at Amsterdam , and that's still much , much better than BRU , I can go every week to BRU but for making a long trip to AMS it must be perfect weather , I hope I can post a nice log and some pictures this weekend.