I don’t see how you can possibly do better than
struct city { string name; int zipcode; };
There’s nothing non-essential there. You need the types of the two members, your whole question is predicated around giving names to the two members, and you want it to be a unique type.
You do know about aggregate initialization syntax, right? You don’t need a constructor or destructor, the compiler-provided ones are just fine.
Example: http://ideone.com/IPCuw
Type safety requires that you introduce new types, otherwise pair<string, int> is ambiguous between (name, zipcode) and (population, temp).
In C++03, returning a new tuple requires either:
city retval = { "name", zipcode };
return retval;
or writing a convenience constructor:
city::city( std::string newName, int newZip ) : name(newName), zipcode(newZip) {}
to get
return city("name", zipcode);
With C++0x, however, you will be allowed to write
return { "name", zipcode };
and no user-defined constructor is necessary.