Italy/Slovenia/Croatia

For me, Venice has more to see and do than any other single spot on your trip. If you mean Camping Rialto on the mainland, then you'll need time to get to and from the city each day.

Are hiking and adventure sports the main focus in Slovenia? Or what do you plan to do with all that time? I haven't stayed in Bovec nor driven that road, but 4 nights seems like a lot, in addition to 3 nights at Lake Bled. I'd also rather have a car for this area.

If you pick up a car upon departing from Venice or Udine, you can return it later to another part of Italy. Be sure to clarify when booking that you need to drive to Slovenia and Croatia and check that paperwork matches that request.

If the kids want to see more, have they suggested specific stops that would fit along this route? I think you could tighten up the time in Slovenia to allow a "proper" 2-night stay (full day to sightsee) in the Cinque Terre and again around Orvieto, Civita di Bagnoregio, or other hill town.

1. You only have one day for Venice - July 13. That seems very light.
2. Bled has awesome hiking if the teens are into nature.
3. What were you planning to do in Pula for 3 days ?
4. How will you get from Pula to Florence ?
5. Civita requires a car.

It would help to get some more details. Are you planning on renting a car for any portions of the trip? Also, do you plan to take a car ferry from Pula to Venice (maybe drop off the car there and do the rest of the trip by train?) and drive from there to Florence, or were you going to drive around?

And what are you planning to do with 4 nights in Bovec, 3 nights in Bled, 3 nights in Pula? What do the kids enjoy? I ask because there's not necessarily that much to see in these places. You could do some day trips, but it would be easier to give you advice if you shared a little about what kinds of activities you want to do.

On paper, it'll certainly work for you. Hopefully some of the youthful energy will come your way. It's a lot of stops for one trip.
Civita is not somewhere people usually stay, as it's a tiny little hilltown. Most people would stay in Orvieto--just to the northeast. And many travelers turn in Hertz rental cars there and take a train into Rome Termini (70 minutes.)

Thank you all for your responses. We all love hiking and water exploration so that is why we gave so much time to Slovenia as it is our understanding that there are lots of outdoor activities to choose from. We will be staying in camp sites for the most part. Croatia is on my son's bucket list. There are some architectural or historic highlights there he was interested in. It makes sense to cut it out, but it does look beautiful and he really wants to go. Anyone who wants to give me arguments for or against, I'm all ears.

I'd like a car in Slovenia, but I haven't figured out how to do that with different drop off and pick up points. I was thinking we would take a ferry from Pula to Venice, and then a train to Florence. We have access to a time share in both Florence and Rome so I wasn't thinking we'd want a car there. It looks like we can get a train to CT and that cars aren't even recommended there. For Civita, I know it's tiny but we will be splurging on a nice restaurant there and since we don't have a car, thought it would be nice not to have to catch a bus late at night. I've just been plugging in locations on Rome2rio and it looked like we could do that (catch a bus), but I'm open to renting a car. I just haven't figured out where and how it makes the most sense to do that with our itinerary.

In summary, we all love the outdoors, but my son is a history buff and we are definitely interested in the museums and more typical tourist things too. It is painfully evident that we need a full two months to see and do everything we want to.

This additional information is very helpful.

Here's what I'd recommend:

July 12: pick up rental car at the airport and drive to Udine
July 13-14 Bovec or Kobarid
July 15-16 Bled
July 17-18 Ljubljana
July 19-21 Rovinj
July 22 drive to Pula and explore before taking car ferry back to Venice. Drop car.
July 22-24 Venice
July 25-28 Florence
July 29-30 CT
July 31 Civita
Aug 1-4 Rome

You could tinker with this a little, add a day here and subtract from there, but this might make better sense.

I think it'll be easier to rent a car when you arrive at the airport in Venice and save Venice for later, since you'll have to come back to Venice anyway. But you could always keep the order as you have it if you think that would work better for you.

I suggest Kobarid as an alternative to Bovec mostly because I didn't go to Bovec, and Kobarid has two excellent features: a great WWI museum and the Kobarid Historic Trail, an excellent hike. You could easily stay in one and day-trip to the other, so it doesn't matter that much I guess.

I suggest Rovinj instead of Pula because it's a better location as a base for exploring Istrian hilltowns. You can still go to Pula to see the amphitheater, either as a day trip or on the day you catch the ferry back to Venice.

I've been to Istria but not yet to Pula. I believe its main tourist feature is Roman ruins--perhaps less important to you since your trip includes Rome?? Rovinj is very picturesque and lively, but I don't know how available budget-level accommodations will be at this point; the beach towns in Istria are very popular. I enjoyed the very old inland towns of Motovun and Groznjan. I also recommend the pretty coastal town of Porec.

Although a car would be advantageous for parts of your trip, it is possible to take a day-trip to Civita di Bagnoregio from Orvieto (probably not on Sundays). I don't know whether there's access from other origins. I hope you're traveling light if you are sleeping in Civita itself. It's a healthy uphill walk from the nearest parking area to the vilkage. Perhaps there's some provision for moving luggage on one of the motorized carts they use for deliveries?

It occurs to me that, at least superficially, Groznjan and Motovun are reminiscent of Civita di Bagnoregio. Since the latter is so important to you and takes considerable effort to reach, I might skip the former and transfer a day to Venice.