Both BLT and VGF are attached to premium, deluxe resorts, and thus, the amenities are very similiar. Both offer multiple pools, lots of dining options, excellent transportation options including boat, bus and monorail transit, spa facilities, and so on and so forth. Naturally, the Grand Floridian is the "flagship" resort, and you will pay a premium for that in terms of either points or cash at VGF / GF as compared to BLT / CR. That premium gets you more opulence, so if you like that feeling of luxury, then perhaps the premium is worth the price of admission for you and your family.
If points / money isn't the biggest concern, the decision really comes down to what theme you prefer. One is turn-of-the-century coastal living, drawing themes from the Hotel del Cornado (San Diego) culminating in a beautifully executed resort with great theming. The other is a more "contemporary" (obviously) theme. Some feel BLT / CR to be too "plain" or "sterile" looking. I had this impression of BLT initially prior to staying there, but after my first night at the resort, I must say that I really enjoyed it and felt the theme to be well executed. So much so, that I am returning again for 9 nights this October.
I would love to stay at VGF, and know that I would enjoy it as I love the main resort, but have a hard time forking over the nightly point requirements. For me, I would probably prefer VGF slightly more in terms of theme, but BLT wins out due to better value and having a very similar level of amenities. Also, BLT has one transportation advantage over VGF - the ability to walk to MK - which is a nice perk. Also having TOTW Lounge makes for a really nice retreat to grab a drink and look at the MK / Orlando skyline.