You could fly to Florence via Frankfurt, it is four and three quarter hours. Leaving Dublin at 12.15, landing into Florence at 6pm. Alternatively there are trains direct from Rome but I reckon the trip via Frankfurt is the best for time, it is about an hour and a half longer than the trip to Pisa. Dunno if it works for you but it is at least a better time to land in!!!
There is a very useful downloadable timetable on the DAA website. Fun if you are trying to get to somewhere strange!
Yes, that Ryanair flight gets in very late and sometimes if there have been delays in earlier flights with this aircraft it can be even later ( the plane overnights in Pisa)
I have travelled to Florence also by flying with Aer lingus to Bologna (starts on March 30) and taking the train down to Florence. There is a bus from Bologna airport to Bologna Station (15-20 mins) and hourly train to Florence (journety time 1 Hour)
I have done this route several times. I would suggest staying at the Gal Galilei Airport Hotel at Pisa airport. It's brand new and very comfortable, reasonable prices too. You could then take a look around Pisa the next day before catching the train to Florence. Unlike many airports Ryanair use, Pisa airport is actually close to the City centre. Pisa itself is not a great city by Italian standards but the leaning tower has to be worth a quick look!
A note of caution. Ryanair's "Bologna" is actually Forli which is miles away. While this might be okay for travelling to Bologna or the Adriatric coast, it takes longer to get to Florence from here than it would from Aer Lingus's version of Bologna.
Have you looked at a connection through stanstead. The landing time is a bit more respectable and you could enjoy a night in Pisa before moving on. I was pleasently surpriced with Pisa. Look into it. Flight times may have changed but that was the route we took.
I have done this route several times. I would suggest staying at the Gal Galilei Airport Hotel at Pisa airport. It's brand new and very comfortable, reasonable prices too. You could then take a look around Pisa the next day before catching the train to Florence. Unlike many airports Ryanair use, Pisa airport is actually close to the City centre. Pisa itself is not a great city by Italian standards but the leaning tower has to be worth a quick look!