I use two week sprints intentionally, and with a purpose. The reason is that I never want my story points (defined through a Fibonacci sequence of 0, 1, 2, 3, 5, 8, 13, 21, 34, etc.) to be considered hourly estimates.
It's also much more flexible when it comes to managing sprints of different lengths for different team members, assessing blockers and interrupts, and clearly defining "estimates" as opposed to unrealistic "deadlines".