I'm surprised the use of BI tools that integrate with Excel has not come up in this discussion. For example, Oracle EssBase (part of Hyperion) is comparatively

I'm surprised the use of BI tools that integrate with Excel has not come up in this discussion. For example, Oracle EssBase (part of Hyperion) is comparatively inexpensive, and it is used in Excel via their SmartView plugin. You get all the power of Excel with live data, and flexible data models driven by an OLAP datastore. It has revolutionized our month-end and commissions process (now takes a fraction of the time), while still allowing the flexibility of Excel.