Huge List of Quality WP7 Development Tips
blogs.claritycon.com
blogs.claritycon.com
In my opinion, you will always be better off using the bare minimum amount of XAML. XAML is completely unnecessary and is a huge barrier to adoption of WPF/SL. You've been better off avoiding XAML this Since SL2; heck you've been better off since WPF beta. That means no databinding, avoid converters, and do the layouts in C#. I.e., not the way the documentation tells you to do it. In fact, much of the list boils down to the above advice.