I might add that the 24 + 11 month maximum validity of the Senator status makes it convenient to combine with another FFP that runs in a 12 month cycle. As a Senator you may go negative in your account up to 160K miles (before that feature was published, you had paper vouchers, but they are gone effective 31/12, sigh!).
The most important benefit for me (besides the booking guarantee) is the general M&M option to upgrade any published fare (even in deep discount land). Since you are flying F, this won't matter to you that much.