You've said the show is as much about marriage as about espionage.
Espionage adds drama and raises the stakes, but the thing people are going to care about is this couple and whether or not they make it. We already know how the Cold War ends. Nobody knows how this marriage will end. Plus, deep down, I'm more interested in marriage than espionage. Maybe I shouldn't admit that.
The Americans' title sequence contrasts the iconography of the U.S. and the USSR--say, a Jazzercise video next to Cossack dancing. Is the message that we were never so different after all?