Microfluidic devices having a plurality of functional features for performing one or more fluidic operations in parallel are provided. Reagents, samples or other fluids common to multiple functional features ("common fluids") may be input into a microfluidic device or system through one or more distributing inputs that divide and distribute the common fluids as desired. The use of a multi-layer fabrication technique allows multiple distributing inputs to distribute to multiple functional features in a microfluidic device without undesirable fluid channel intersections.