These are two awesome but very, very, very different options.
If you're sure that you'll return home after B-School to work at your family's firm, I think you should just pick the program you think you'll enjoy the most (which definitely includes location and lifestyle). There are some striking contrasts between IESE and Ross:
Barcelona vs. A2
Europe vs. US
Private Religious School vs. Massive State School
Mediterranean vs. Upper Midwest
Futbol vs. Football
etc.
On the other hand, if you think you may want to leave the door open for recruiting options post-MBA, it makes the decision easier IMO. I think IESE is the definite choice if you want to be in the EU, Ross is the clear winner if you want to be stateside. (Anywhere else internationally it'd be harder to tell I am guessing.) It's awesome that both are 2-year programs and you can do an internship and decide for certain.
Good luck with the decision!