Male/Female is definitely the best combination. Male/Male is next. Two females is not recommended because there is great potential when they get older they will fight. Sometimes to the death.
I got Riley when Max was 7mos old. It was one of the best decisions I have ever made. They both play so much. Max even waits for Riley to do anything. Also, I will say where is Riley and Max will go get her.
Maxwell-8/10/05 Brindle Docked and Floppy
Riley-3/27/06 Flashy Fawn Docked and Floppy