25th Large Installation System Administration Conference (LISA '11), December 4–9, 2011, Boston, MA
Usenix LISA 2011 is a very large, mostly Unix-y conference. It has a reputation for being a bit academic, recently had adopted more practical / DevOps stuff. I'm the co-chair of 2011 and we are increasing the focus on topics that mean you go home with something you can directly use. For example, in addition to "papers" (which are usually research-y) there we have a series called "experience reports" which is people recounting major projects they've done (like, migration to a new email system) and what lessons they learned.
The half-day tutorials are what most people go for as they contain training that you manager will see the inherent value: specific technologies, skills, etc. There is also a Wed/Thu/Fri "technical sessions" program which is talks, papers, and contains more of the "research"-y presentations. One of my favorite tracks is the "gurus" sessions, which are Q&A sessions hosted by various sysadmin rockstars (for example, the author of Postfix himself, etc.)
The program will be announced in July. Registration opens around the same time.