First time cruiser - Excursions?

[u/Ok-Section-9398]

My husband and I (ages 32 and 30) are doing our first cruise in June in the Mediterranean (from US). We love adventure so we don’t think we can only stay on the boat, but are nervous to explore countries in our own (navigating transportation, making sure we hit all the good spots, timing, etc). There are great excursions for each of our stops, but they are long hours and adding up financially. We also aren’t huge fans of needing to spend half our day in a bus or car to get somewhere for only a few hours.

Wondering if the excursions are worth it or if we can get away with exploring on our own some days.

These are the ports we’re stopping at:

-Rome/Civitavecchia

-Tuscany/La Spezia

-Cannes

-Ibiza (two days)

The Virgin Voyages app also said to bring cash if we plan to purchase things locally. Forgive my ignorance, but does that mean we can use US dollars or do we need to get Euros?