We're traveling towards the end of August and are planning a train from the airport to Florence and will stay there a few days. We land at 1330 and will have luggage. Has anyone done this? Advice appreciated.
Sure, lots of forum posters have. You asked this same question back in February and received some helpful replies so did you forget about that thread, didn't know where to find it, or have additional questions people can help you with?
https://community.ricksteves.com/travel-forum/italy/trains-from-rome-airport-fco
After collecting your luggage, follow the "Train" signs to the airport railway station.
At the counter ask for a through ticket to Firenze SM Novella station.
FCO is served by two lines: the fast train goes direct to Roma Termini station, the slow one goes to the smaller Roma Tiburtina. All high speed trains from Rome to Florence stop at both stations. It makes no difference.
Don't get these train tickets in advance, flights can be delayed and discounted tickets can't be changed.