Are Your Agile Retrospectives Growing Stale?

The other day I stumbled upon Michael James' ScrumMaster Checklist and decided to fill out and see where we were at as an agile team. While I'm not going to go into detail, there were some things that caused a great deal of self-reflection for me; in particular:

Have you tried a variety of formats and locations for Sprint Retrospective Meetings?

This is something I've been wanting to do since last time I decided to breathe life into our agile retrospectives with great success. While this method has been a tremendous format for gathering feedback on the previous sprint, it seems that the team is getting a little too familiar with how it's supposed to go. Another problem is certain team members struggle to think of two positives and negatives in advance of the meeting so we waste time as they frantically try to get something on paper.

In researching different formats that people have used, I stumbled across this list of agile retrospective formats and think I'll be rolling out the 6 Thinking Hats Retrospective Plan for next week's retro. I'll be posting my experiment on my blog when the results are in!

What kind of formats have you used in your retrospectives? Any thoughts or suggestions are much desired.