<p>Can someone tell me what the statuses mean in SQL Server's sp_who command?  Why might a spid be suspended?  What does it mean to be "runnable"?</p>

<p>Thanks!</p>

Pretty easy to find answer online.
Link
dormant.
SQL Server is resetting the session.
running.
The session is running one or more batches. When Multiple Active Result Sets (MARS) is enabled, a session can run multiple batches. For more information, see Using Multiple Active Result Sets (MARS).
background.
The session is running a background task, such as deadlock detection.
rollback.
The session has a transaction rollback in process.
pending.
The session is waiting for a worker thread to become available.
runnable.
The session's task is in the runnable queue of a scheduler while waiting to get a time quantum.
spinloop.
The session's task is waiting for a spinlock to become free.
suspended.
The session is waiting for an event, such as I/O, to complete.