I'd agree with Lugia on every single point and add - more utility modules...
think of them as plumbing... copying signals (stackcables or hubs are great for non-pitch signals, otherwise buffered mults)... logic, sequential switches, offsets, sub-mixing, matrix mixing (see my post on the matrix mixer thread for why) etc etc etc... possibly the most important modules you can add - and even better they are generally comparatively inexpensive...
and see my signature for a formula to follow, loosely, that gives you the most versatile modular for the least expense... scales well too - from tiny to massive modular synthesizers...
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities