It looks like the 'survivors in growing classes' filter that we've added in v7 of the profiler may do some of what you need. The new categorisation view in the class graph may help as well.
You can get the EA build of version 7 here: http://www.red-gate.com/MessageBoard/vi ... .php?f=134
From your description, one possibility is that the objects you're having problems with have finalizers (or they are referenced by something with a finallizer, a UI control perhaps). These will cause them to survive at least one garbage collection, and potentially very many if finalizable objects reference each other (in the profiler this will look like they gradually disappear over the course of many snapshots).
The zombie object filter might be worth checking out as well: this will show you any objects that were going to be finalized in the earlier snapshot but haven't been removed in the later snapshot - this can be sign of poor finalizer code that creates new references to the object, forcing it to stay in memory. It can also be a sign of slow finalizer code, which will limit the rate at which .NET can remove the objects.