I make it a point to visit all the sites in Belgium (that includes every belfry and beguinage). My vision on this is that: if I travel thousands of kilometers to see nice things, why not see the nice things in my own country as well? I get the feeling people somethimes skip sights in their own country, simply because it's in their own country, while your own country (that's the last time I say own country I swear) can have a lot to offer.
I have to admit, some seem less impressive, but that's mostly cause of the fact that they are like 20 minutes away from where I live. and I can visit them frequently. I often pass the belfries in Antwerp, and Plantin-Moretus I visited with a schooltrip. I really like Bruges, cause it's so pretty and it keeps amazing me.
I always really liked the flemish beguinages. Cause if you had asked me before 1998 what sights flanders could possible offer that are of universal value, I wouldn't be able to come up with any. the beguinages added something to our cultural identity in my humble opinion. Though the novelty wears off a bit after you've seen a few. Same with the belfries. Though I like visiting places in Belgium I'd usually not visit (thanks to the belfries).
The Grand Place in Brussels stays pretty awe-inspiring.
So in short to answer your question: somethimes I do enjoy them as much as abroad, somethimes not. And visiting sites in far of places also gives an extra dimension to a visit, since they are harder to reach.