Congratulations on your admissions to Amherst and UChicago with a possibility at Pomona. I am writing from the perspective of a university academic in a non-economics business field. I am an alum of the college at UChicago.
UChicago is superb at teaching how to think in a way such that doing research comes naturally to you. You will have the opportunity to learn directly from the thinkers who are shaping the direction of their discipline.
As you study economics you will see that interfacing with ideas and methods in other fields (i.e. sociology, statistics, psychology) can be very helpful. Chicago is an unmatched powerhouse in the social sciences and you will be exposed to important developments in disciplines related to your own.
UChicago’s common core was wonderful in that it exposed me to thinking in a wide range of disciplines. You don’t realize how helpful this can be until you need to solve a problem and a tool or technique from another field does the job. UChicago gives enough exposure to many fields such that you feel comfortable dipping into them and pulling out what you need. UChicago has experts in many fields so that you will find your wide ranging academic interests will be satisfied. You said Amherst’s curriculum was “flexible” with no requirements. I believe that is a negative for intellectual development.
You mention Amherst reportedly has a social divide between athletes and a non-athletes. Personally, I exercise for at least an hour each day but I can think of nothing so boring as listening to sports fanatics ramble on about games, teams, and players.
You mention LAC’s as being strong in enabling the forging of relationships between professors and students. At UChicago faculty seemed to have an open door policy and I was able to develop excellent individual relationships with them.
If you wish to go to graduate school in economics and you do your undergraduate work at Chicago you are coming from the best. Also, you will likely have an advantage in applying to UChicago’s PhD or MBA programs you will not have if you attend Amherst or Pomona.
The arts scene at UChicago is outstanding and there is close access to downtown Chicago’s array of theater, ballet, opera, the Art Institute of Chicago, the Chicago Symphony Orchestra, etc.
You have an interest in urban policy. I would be concerned that this is not a strong area at Amherst.
You mentioned an interest in working in the U.S. after graduation. I believe UChicago has a deservedly outstanding reputation in the U.S. job market. Unfortunately, in the workplace (especially outside the east coast) you will meet with many people who are not familiar with the high standards at Amherst.