Need help finalising itinerary in Croatia

Are you making side trips from Dubrovnik? The walled city itself is very compact - unless you're going to Montenegro or doing some day trips out of Dubrovnik, 4 nights is a bit much. You can see all of Dubrovnik leisurely in 1.5 days, so I would consider putting extra nights elsewhere.

Can you clarify where you're flying into and out of?

We are flying in and out of Split. I was hoping to see Montenegro and do some sea kayaking, but I know my wife could kill several days just relaxing. I'm trying to find a good compromise. Both of us are scuba-certified so we might consider that, but I think there may be better dive sites off some of the islands.

If I cut a day in Dubrovnik, would it be better spent on Zadar, or somewhere else near the end of the trip?

I haven't been north of Split (so my comments are limited), but would recommend stopping in Trogir which is very close by. It's much more compact and very charming, I think you'll enjoy it. Also, I'd highly recommend going to Korcula and driving through the Peljesac Peninsula, which is gorgeous and has wines you can sample (if interested). Vis is a very small island in Croatia, so going to another one (just to compare) may be fun - there are several choices (Korcula, Hvar, Brac, Mljet, the tiny Lokrum island off Dubrovnik). Of these, I've been to Lokrum (just OK, very small), Korcula, and Brac and really liked the latter two the most...Korcula had a very Venetian feel to it and Brac had the most beautiful beach (at Bol, called Zlatni Rat).

How many full days do you have on this trip? It won't be hard to fill up the days just with what you have, without even needing to drive up to Zadar.

I can give my subjective opinion of Zadar - which is like asking my favorite flavor of ice cream. ;-) I thought Zadar was OK not amazing. I had only a night there but that was enough. But it didn't really "float my boat" and I can't really explain why. The Sun Salutation and the Sea Organ are interesting and worth seeing if you are in Zadar but otherwise not worth any detour, for people who think they sound interesting. The town has old Roman ruins scattered around the area of the old forum and there are some interesting buildings. But I didn't feel compelled to stay longer.

Some people do love Zadar. It really depends who you ask. I stopped for a few hours at Sibenik to the south which I really loved. Not as touristy as Zadar, very different. It reminded me a little of Lucca, Italy, with narrow streets between tall old buildings.

You might start in Split, take a bus to Dubrovnik for a few days (where you probably don't want a car), then rent a car as you leave Dubrovnik and drive to Montenegro the last day, then drive back via Mostar and back up to Plitvice etc. I liked having a car to drive to Kotor, because the scenery along the Bay of Kotor was amazing, and I stopped numerous times for pictures. I also stopped in the beautiful town of Perast. Consider taking one of your nights from Dubrovnik to stay a night in Montenegro.

If you wind up driving from Kotor to Mostar (which is what I did but split over two days), you could stop for a few hours in the Bosnian town of Trebinje, which is not particularly charming but is also not very touristy (unlike Mostar). There's a neat old stone bridge (which was disassembled and moved to its present location several decades ago) and a beautiful Serbian Orthodox church up on the hill overlooking the whole valley and the town. I spent a night in Trebinje, but a few hours to stop is probably enough. Mostar is great but not huge, and because it gets a lot of tourists mid-day you might enjoy it more at night when it is less crowded.

Trogir is much smaller than Split and more charming in my view - but less interesting. But I like your idea of spending the final night there if you will already see Split in the beginning; being close to the airport is a plus, but unless you have a super early flight, it probably doesn't matter. Parking a car in Trogir may be easier than parking one in Split, though.

I'm assuming 11 full days, but we want to have some downtime on the first few days before the driving starts. I have no problems with the driving between interesting places, but my wife is less keen on that. She would be fine with the 4 days in Dubrovnik to catch up on reading, but I know she hasn't spent time looking at the scale of some of these places.

The Bay of Kotor looks amazing. When I think about the time involved in renting a car for a day (and the possibility of spending time waiting at a border), that I prefer the idea of staying one less night in Dubrovnik, and driving to Kotor as part of the return journey. Buses are fine too, but I prefer to have flexibility to take photos where I want.

If you drive from Dubrovnik to Montenegro, consider the alternate border crossing at Konfin (described in Rick's book). The crossing is a little bit of a detour, but it's too small for buses to use, so it can't back up with tour buses. In early May of 2015, I had to wait 5 minutes to cross there only because the guard on the Croatia side was on his phone for five minutes before he decided to hang up and check me through. No one was in front of me.

If you drive from Montenegro directly to Bosnia (without crossing back into Croatia) as I did, note that there is some sort of tax paid (a few Euros) as you leave. There used to be a similar tax when exiting Croatia to Montenegro, but since Croatia joined the EU, that tax has been removed.

Instead of staying in Split, we stay on Brac and take the ferry in as we like. I also prefer Sibenik to Zadar.

I spent a short half-day walking around Zadar in 2015 and wished for more time there, but I don't think it's a place you have to go on this trip. I haven't been to Sibenik, so I can't compare the two. In Montenegro, Herceg Novi is just off the route to Kotor and is worth a stop.

Four nights in Dubrovnik sounds like a lot to me, too, given that there are so many interesting options in the area.