Been thinking on & off (mostly off). Why not jump the gun, so to speak?
Let's say I retire early March '16. That would give me about 70 days to obtain ~550 (valid) signatures to get onto the Nov'16 ballot for state rep. (actual deadline is May 23rd) The idea would be to get those 10+ sigs per day by going one-on-one with the voters either door-to-door or at events. This would be a lot cheaper than paying the filing fee and it combines petitioning with campaigning. Assuming you have your candidate website ready and some handout card ready, this is an efficient use of time. So you've got a on-ballot candidacy at a cut-rate cost but since it's all rush rush last minute stuff, what do you really expect to get out of it?
Well, a tiny headstart on the 2018 statewide effort for one thing. If your short local campaign puts extra focus on local groups affiliated with larger statewide (or national) organizations, that can be particularly useful. Also, there's no reason why a well thought out and organized ( a relative concept based on what I've observed as some pitiful efforts of recent statewide NPA on-ballot candidates) campaign for state legislature can't be pitched to potential "big fish" donors throughout Florida just as readily as a federal legislative campaign. Again, it's at least a tiny introduction to these players. It also could mean the senate campaign starts off with a small pool of volunteers rather than zero. And it's a limited investment shakedown which could prove whether I'm actually up to all this 2018 business or not.
Update:
I don't know... the current thinking is to lead in with a federal issues website morphing into candidate campaign(s). If there's going to be a 2016 campaign, it probably(?) needs to be Congress. But for that, petitioning is much much higher - ~4,500 (valid) which is going to require a very early start against the May 23, 2016 deadline. The other option (fee) is expensive. >$4,000, which pretty much guarantees FEC filing due to the $5,000 threshold for reporting.
