I'd take a different tack, and loop through the placemark nodes.

I've also assumed the OP wants all coords, rather than the last one as per your example, so have dumped them in a hash of arrays...

my $xml = 'your xml...';
my %coords_by_name;

while ($xml =~ m{<Placemark>(.*?)</Placemark>}gs ) {
    my $placemark_snippet = $1;
    if ( $placemark_snippet =~ m{(<name>.*?</name>)}gs ) {
        my $name = $1;
        while ( $placemark_snippet =~ m{(<coordinates>.*?</coordinates
+>)}gs ) {
            push @{$coords_by_name{$name}}, $1;
        }
    }
}

use Data::Dumper;
print Dumper(\%coords_by_name);
[download]

I agree with the other comments though, you need a good reason to not use a proper xml parser, the above code won't be very robust, and only supports a fraction of the valid ways you could write that xml.