What are good ways to prioritize campaigns and emails?

Today my company uses an IBM marketing automation platform, and we're in the process of shifting to Eloqua.  In our business our customers might have interest in several of our product families, and could be included in segments for many product areas and campaigns at once.  We took "marketing automation" to heart, and developed a sophisticated set of flowcharts driven by rules on touch frequency, country holidays, and more that determine what email each contact should receive on any given day.  These help us balance customer interests and let us have dozens of campaigns running at any one time.

As we shift to Eloqua, we're looking for ways to perform similar functions while also distributing mailing authority more broadly in our marketing teams.  I've seen posts here about how people manage email frequency.  Have any of you developed tools to manage customer priorities among multiple campaigns and email streams?  If one of your customers might be interested in several of the campaigns you're running, how do you decide which one the customer enters?  Thanks in advance for your wisdom!