As you travel through several countries a Globalpass :)
If a Consecutive or Flexipass depends on how many places you wanna visit and how long you wanna travel at all. Poland,Czech Republic & Hungary are quite cheap to travel by rail (Maybe combine a Interrail Flexpass for the expensive routes through Germany & down to Italy.

Please note you have just one outbound (to leave the Netherlands) and one Inbound Journey (to enter the Netherlands) included. Means that you have to pay atleast 2Journey´s within your Country to the border.

A easy way from Netherlands to Florence is ICE via Frankfurt to Munich and from Munich with the Nightjet in direction Rome till Florence.

Backwards you could travel Florence - Verona - Eurocity - Innsbruck - Nightjet - Netherlands

or Florence - Milan - Switzerland - Zürich/Basel - ICE or Nightjet - Netherlands

Dear @seewulf , thanks for your reply! And also sorry for my late response. I have another question: if I want to travel from Amsterdam to Florence on August 4, I can leave from Amsterdam in the afternoon on August 4 and arrive in Florence the next day in the morning. I will have to switch one more train on August 5 (see the screenshot below). Does this then count as two travel days or just one? 

Kind regards,

Max

This is two travel days since you're changing trains after midnight.

Thanks for your reply @rvdborgt . I bought a 7 day pass a while ago, but my travel plans have changed. I am going to check if I can exchange my pass for a 10 day pass. 

For exchanging a pass, check this page.

Note: for VNZ-Fir just take local=regionale train, without any REServ or surcharge to worry about.

@mcadv good to know, thanks!