Qantas Boeing 747 seating question

If anybody is familiar or has traveled from US to Australia on their
747 aircraft, maybe you can help me with this question:

My wife and I are planning our first visit to Australia departing from
LA. We would prefer not to share the long flight with a stranger seated
next to us in the 3-seat rows by the windows (Economy).
There are a few 2-seat rows (70 through 73) at the very back (see
:http://www.seatguru.com/airlines/Qan...ng_747-400.php)

Are they too noisy, too crowded as people line up to use restrooms, or
is there any other downside to them?
I will appreciate any comments or opinions.

thanks

Paul