Answer:
A random search for flights from Miami (MIA) to Reykjavik (KEF) shows:
OPTION 1: 9hr 45min via Boston Logan (BOS)
MIA - BOS American Airlines Flt 1926 Dep 03:55pm 17Feb,wed
BOS - KEF Icelandair Flt 630 Dep 08:35pm 17Feb,Wed
Flight Duration: 8hr 15min; Layover Time: 1hr 30min; Total Trip Time: 9hr 45min
OPTION 2: 14hr 15min via London Heathrow (LHR)
MIA - LHR British Airways Flt 208 Dep 08:45pm 19Feb,Fri/20Feb,Sat
LHR - KEF Icelandair Flt 451 Dep 01:00pm 20Feb,Sat/21Feb,sun
Flight Duration: 11hr 20min; Layover Time: 2hr 55min; Total Trip Time: 14hr 15min