Answering my own question, from Civ V - Map Size/Game Speed REFERENCE (Mechanic Changes and Map Specifications):
So, given default settings, and therefore no compelling reason to play wider than usual -- huge maps means significantly happier cities and several more social policies! Reading more, beaker cost increases ~10% from standard to large to huge.
MAP SIZE DETAILS (Mechanics that vary with Map Size alone)
DUEL
Unhappiness Per City = 2, Extra City Policy Penalty = 30%
TINY
Unhappiness Per City = 2, Extra City Policy Penalty = 30%
SMALL
Unhappiness Per City = 2, Extra City Policy Penalty = 30%
STANDARD
Unhappiness Per City = 2, Extra City Policy Penalty = 30%
LARGE
Unhappiness Per City = 1.6, Extra City Policy Penalty = 20%
HUGE
Unhappiness Per City = 1.2, Extra City Policy Penalty = 15%
So, given default settings, and therefore no compelling reason to play wider than usual -- huge maps means significantly happier cities and several more social policies! Reading more, beaker cost increases ~10% from standard to large to huge.