Well, I'll kick in here. It's really hard to say where to go with this because there are so many different directions to go. I guess: what are you thinking you would like to do with this setup? And if you already own the Mother-32, Wasp filter and such, then you already have quite a bit there. I can tell you about the Erica Synths modules. They are top notch (but their Fusion line is expensive). I have their Fusion Mixer and I love it. Without knowing how you might want to use this setup, it's hard for me to say. If you're just looking for drones and sound scapes, then the Mother-32 is a place to start and then adding another noise source or oscillator. Go slow. It's an expensive domain here. In fact, now that I think of it, the Wasp filter and Wiard Oscillator fed into the Mother-32 might be interesting. You already have these. You mention other analogue synths. What other synths do you have? Because you already have a modular system going here.
cheers / alex