I think it would be really sweet to be able to run Omnisphere "minimal-GUI" mode, to save some screen space.
The host sequencer together with all plug-ins tend to clutter the screen completely. I am using Logic 8 with a 24 inch monitor.
For example, this GUI would only include 4 parts, each with a volume knob (not slider - uses too much screen space), pan knob, and 4 aux knobs.
No fancy frames or whatever. Just a minimal GUI. I know, this will not LOOK impressive but I do not think that is needed with Omnisphere as the SOUNDS are so good.
My reason for going with only for parts is mainly because that is what I use as a maximum on a per-core basis. I run a 8-core Mac Pro, and usually I use max 4 parts per instance of Omnisphere, as each instance can utilize only one core.
In general, I hope all SW plug-in companies will pick-up on this idea. In the longer run, perhaps Logic and Cubase etc will add to the AU/VST protocol to make it possible to even more closely integrate different SW plug-ins with the sequencer SW. I would want to be able to make 3rd party SW plug-in patch/voice selections in the track header in the arrange window. That would be really really sweet...