I stayed at both last summer..started with 4 nights at BW in a studio, then 3 nights in a studio at BLT, then 4 nights in a studio at WL. I have to say, that while the studio at BLT is a bit tighter than the studio at BW, it isn't tiny. There were three of us, myself, dh and dd, 17. We had no issues at all with space at BLT. In fact, I found the space to be much more usable than the space at BW...go figure.
My only issue with BLT studios with two kids is sleeping arrangements. Will the kids share the fold out sofa??? It's certainly big enough. There just isn't any room for an addtl bed anywhere.
But....BLT is a great choice if you have young kids. The walk to MK is under 10 mins and very safe. Kids seem to like being at MK more than the other parks, so the monorail resorts are a huge plus.