The boxing game is great and a good workout too! I was dying after playing last night too. Rach kept going back for more though!
The tennis was fun but I didn't do very well. I can't wait to try that when we have 2 remotes and can play against each other. I though I did OK with bowling until I read what Robin scoresI haven't tried golf yet.
When I play DS in tennis, I only use my back guy. When I play the computer, I will use the front guy and twist the controller a little too. It puts some spin on the ball.
I think I boxed 8-10 matches on Xmas morning. It gets harder as you get better. I knocked out everyone except my last opponent who I won the decision 2-1.
I stopped after that one. I was tired.