From the US, we plan to round trip to Venice and then train to Padua for the first night on the ground. Then we have the following travel plan https://photos.app.goo.gl/RCTbsc9YE6rf6XBg9 (reproduced below if the link to the map fails):
🗓️ Padua | May 12–14 | 🌙 3 Nights
🗓️ San Marino | May 15–16 | 🌙 2 Nights
🗓️ Ancona | May 17–18 | 🌙 2 Nights
🗓️ Ferry (SNAV) | May 19 | 🌙 1 Night
🗓️ Split | May 20–24 | 🌙 4 Nights
🗓️ Zadar | May 24–27 | 🌙 3 Nights
🗓️ Rovinj | May 27–30 | 🌙 3 Nights
🗓️ Ljubljana | May 30–June 3 | 🌙 4 Nights
🗓️ Trieste | June 3–6 | 🌙 3 Nights
🗓️ Venice | June 6–10 | 🌙 4 Nights
We are lightly experienced international travels (when compared to others in this forum) and have been to Venice previously, but only for 3 nights. We have not been to any of the other locations noted. We are aware of the difficult transfer from Zadar to Rovinj on May 27, and plan a private transfer. Our limit on a bus is 5 hours (from experience) and we don't rent cars overseas (long story). Our first draft of this trip included Dubrovnik, but the ferry departs from Bari and we've spent 5 nights in Bari on another trip so we moved Northward to Ancona / Split.
So, I look forward to your comments and thank you for your time.