7 Days in Croatia--Suggestions Welcome :-)

You should visit Trogir as an easy day trip from Split. It is an absolutely charming town about 1/2 hour drive from Split, also accessible by bus.

Somewhere along the way, either on the way from Split to Zagreb or as a (long) day trip, you'll want to be sure to visit Plitvice National Park. You might want to consider spending the night there on your way to Zagreb.

My top recommendation would be Plitvice Lakes National Park unless you're unlucky with the weather, by which I mean heavy or persistent rain. It would be best to spend the night before your park visit as close to the park as you can so you beat the day-trippers onto the trails. I don't know about late-September/early October, but the park can be unbelievably swamped (I mean peak-season Venice- and Cinque Terre-level swamped). You can go from Split to the park and then on to Zagreb by public bus in the summer. I assume that will still be possible at the time of your visit.

Zadar is a nice coastal town north of Split with a picturesque old town. Worth a half-day stop if you happen to have the time, but I think most people would rank an island visit higher. Zadar's much easier to get to, though, and if you happen to have a half-day free on your way to Plitvice or Zagreb, I don't think you'll be disappointed in Zadar.

I enjoyed Zagreb a lot. It has an active café culture and a youthful vibe. The hilly old town is very pretty and could easily absorb an entire day for just walking around. There are two fun museums in the upper old town, a small but good museum of naïve art and the "Museum of Broken Relationships". You have to be willing to read a lot of (English-language) text in the latter, so it may not be for everyone.

The area roughly between the old town and the train station has a number of large and quite good more traditional museums. The tourist office has a museum-specific pamphlet that will help you decide which ones might be worth a stop.

There are some markets in the old-town area as well. The tourist office will be able to provide details. There's a branch at the bus station (upstairs) as well as one somewhere in lower part of the old town.

We didn't like Hvar so much - seemed jaded, smug and touristy to me. Loved nearby Korula though, it was one of our absolute favorite places on a trip that was packed with superlatives. Tastes vary.
We were also somewhat let down by Split: when we were there in May, it was completely packed with cruise ship passengers - maybe by the end of October they'll have lessened a bit.
Agree with the recommendations for Trogir (we loved it) and we liked Zadar quite a bit, too.
Of course, Plitvice is tops if you can find a way to make it work - it's worth the time/trouble to work it into your itinerary, don't miss it.
Didn't go to Zagreb so can't help you there.
If you're going to be in Dubrovnik, add a day there and rent a car for the day, drive to Kotor (its an easy day trip). Climb the wall.

Sep 25 Arrive Dubrovnik
Sep 28 Morning ferry to Korcula
Sep 29 Morning ferry to Hvar
Sep 30 Morning ferry to Split (with day to Trogir)
Oct 03 Depart Split

Check ferry schedules here ...
http://www.jadrolinija.hr/en/ferry-croatia

I'd recommend Plitvice National Park (~2.5 hr drive one-way) and Mostar, Bosnia (~2.25 hr drive one-way). Both are worth the trip. If you will not have a rental car, both destinations have group tours available. Hvar is okay, but if you're able to get out of town for a day, do it.

Thanks for the advice everyone! We are thinking of breaking up the trip between Dubrovnik and Split and spending the night somewhere along the way. Any recommendations? Also it seems like taking a bus is the best way to get to Split from Dubrovnik?

If we do go to Zagreb and stop at the Plitvice lakes where is a good place to stay nearby? Can we get a bus from there to Zagreb the next day after we go to the lakes?

Thanks for all the help, really appreciate all the wonderful knowledge on here!!

Paul

Makarska seems like a good place to stay between Split and Dubrovnik and the buses stop there. Yes, it's easy to take a nice bus between the two cities. The trip is about 4.5 hours or so.

I visited Plitvice Lakes N.P. in late August 2015. At that time of year there were good bus connections to Zagreb. I assume you won't have any difficulties at the time of your trip.

You can explore bus schedules on the BusCroatia website. I think there's more than one company doing the Plitvice-Zagreb run. I highly recommend checking on the schedule locally when you get to Plitvice to verify any information you find online. I'm not sure where to do that, however. I don't remember seeing a tourist office in the area. If you stay at one of the larger hotels near the park, it may have information on the bus schedule, but I suspect that the departure times may be a bit uncertain.

Be sure you know exactly where to get the bus. And don't plan to take the last bus back!

I've never spent the night near Plitvice (a mistake on my part), but a visit to booking.com will turn up a number of options. There is at least one large hotel right at the park, but there are other (smaller and probably much cheaper) options not terribly far away. Just be sure you know exactly how far the lodgings are from the park and verify that you'll be able to leave your luggage at the hotel during your park visit.

Also it seems like taking a bus is the best way to get to Split from Dubrovnik?

You can either take the bus or the catamaran. Both take approximately 4 hours. I prefer the catamaran because you can be mobile and at this time of year, it won't be close to full. If you want to stay somewhere along the way, a bus is a better option.