I'd favor a single pin rows rather than double; a double row makes breadboarding difficult, and protoboards are still complicated, as Matthijs points out.
As far as extra pins beyond 32, another GND connection would be nice.
The current v1.0 Scouts have a 22 mm spacing between the pin rows, same as XBee modules. This is 0.87", so if the change is made to 0.1" pin spacing, then the width between the header rows needs to be altered to 0.9" (or 0.8") for breadboard compatibility. For comparison/discussion (I realize only two have radios, and two use ARM processors), here are some 0.1" pin-spacing layouts:
SparkFun/Arduino Pro Mini: 0.6" between headers, two 13-pin single row headers (two sets of extra interior pins) (pins on the end for the serial programming connection)
PJRC Teensy 3.1: 0.6" between headers, two 14-pin single row headers (many interior pads for extra pins)
Spark Core (Photon, Electron, and upcoming BLE): 0.7" between headers, two 12-pin single row headers
LowPowerLabs Moteino (ATMega328p with a piggyback sub-GHz radio): 0.8" between headers, two 13-pin single row headers (pins on the end for the serial programming connection)
Otherwise the closest thing existing to the Pinoccio seems to be the Libelium Waspmote: a much bigger board that uses the XBee footprint for the radio module, and double-row female headers for the sensor inputs.