Using good ole great circle mapper
DXB-UIO = 8904 miles
DXB-MAD-UIO = 8945 miles (=+0.5%)
DXB-AMS-UIO = 9149 miles (=+2.7%)
DXB-SAO-UIO = 10274 (+15.4%)
DXB-LAX-UIO = 11835 (+32.9%)
DXB-MIA-UIO = 9631 (+8.2%)
DXB-NYC-UIO = 9668 (+8.6%)
So theroretically your optimum route would be via Madrid...
The 'however' is that
afaik IB don't serve DXB so you'd have 2 carriers with all the annoyance that involves.
Via Asmterdam you would be 1 carrier all through and with 2 nonstop flights and (from the KLM schedules current) 4 hours in SPL which would give you time to have a shower & shave & have a decent breakfast...
Any other routing looks to be full of misery & hassle (via LAX, NYC, MIA sure to ruin your holidays)