my %tz_lkup = (
    ny => "America/New_York",
    ln => "Europe/London",
    tk => "Asia/Tokyo",
    hk => "Asia/Hong_Kong",
    se => "Asia/Seoul",
    mo => "Europe/Moscow",
);

my $today_dt     = DateTime->now( time_zone => $tz_lkup{$region} );
my $tomorrow_dt  = $today_dt->add( days => 1 );
my $yesterday_dt = $today_dt->subtract( days => 1 );

print "It is now $today_dt in ", uc($region), "\n";
...