Gangolf, you guided me up Paglia Orba on Corsica last year. This year I just happen to be passing through the Alpi Apuane for four days ... what a pleasure to discover you are just ahead of me, posting information for my visit!
Glad to be of help. Must do:
Pania della Croce and Pania Secca (1 day)
Monte Sumbra (1 day)
Monte Nona / Matanna / Forato (1 day)
Monte Tambura (1 day)
Will take a while until I'll have them posted ...
If you come from the west (we didn't) Monte Sagro is a good option and Monte Pisanino / Pizzo d'Ucello from the north.
You have given me quite a bit of homework--which I will enjoy doing! I believe my wife has us based at Fosdinovo, convenient to Monte Pisanino and Monte Tambura, which are both on your list.
Monte Sagro also can be reached easily from there. For all of these mountains yoou should go over the weekends when the marble quarries are not operative. I forgot Monte Altissimo, which you can easily reach from Massa. As for the other suggestions you have to drive a little more ;-)