WiFlySerial and WiFly RN-XV

Have you checked your Streaming library if the << operator is doing what you expect it to do? The standard Print class does not support that operator.

The GET is pushed right up against the 80

This is probably correct as "open www.mysite.com 80" is a command for the RN-XV. You don't see the response to it, which is probably CONNECT. Then you send the data for that connection which directly starts with a GET.