I do it the same as Alegria.
2 plug-in folders. 32bit and 64bit.
And since my memory is shot I do it as I'm installing the plug-in. When it ask's for the .dll path I direct it to either folder. I install everything that can be in 64bit. I only have like 10 plugs that are 32bit.
One thing I do tho is say I'm installing Amplitube. I go to C:\Program Files (x86)\Cakewalk\VSTPlugins and in there I make a new folder named IK Multimedia-32bit.
Now all my IK plugs go into that folder. When I'm in Sonar and go to add an effect I right click the fx bin and see all my plugs. Anything that is 32bit has it right in the name. So I'll see IK Multimedia-32bit and in that sub folder that opens is all their plugs.
This keeps my list shorter and lets me know which plugs are 64 vs. 32.
So I have a Voxengo folder, a Waves folder, a Softube folder, an IK folder and so on.
Mike