Split to Cavtat

The bus (~4 hours) is really perfectly fine in my experience (you'll change to a local bus on arrival to Dubrovnik bus station--they are roughly every 30 minutes), but you could take a boat part of the way, switch to bus on arrival in Dubrovnik.
See catamaran schedules on the Krilo and Jadrolinija websites for options to break up the trip.
Bus schedules:
https://www.ak-split.hr/en/departures-from-split/
https://autobusni-kolodvor-dubrovnik.com/en
https://visit.cavtat-konavle.com/en/arrival
As far as lunch, if you wish to get on to Dubrovnik and have lunch there, you'll have to find a luggage storage place. There are some at the bus station/port, but you'd have to go back and forth. If you can pinpoint the bus departure from old town and find a luggage storage facility in old town, that might reduce backtracking. Or at that point, just take a taxi as it is not that far to Cavtat.

I think 6 nights is a bit much for Split. I’d cut that to 3. And spend the remaining 3 nights on the gorgeous island of Vis. Be sure to visit (or possibly stay in) the little fishing village of Komiza, where you can take a boat to the blue cave of Bisevo. Choose a sunny day for this — it’s spectacular.

The ferry leaves Vis, returning to Split, very early in the morning. You can walk across the parking lot at the dock and catch a bus to Dubrovnik — where you’ll need to change to another bus for Cavtat. Check the bus schedule and pick-up location while you’re in Split.

We did this exact trip once —a few days in Split, ferry to & from Vis, bus to Cavtat. It was easy & fun. We love Cavtat. You can find day trips at the harbor — boat trips to other islands, or a bus tour to Montenegro. Great trip.

The bus just might work! We would likely take a taxi from Dubrovnik to Cavat.
Do you have any experience with a ferry(s) from Split to Dubrovnik?
As for 6 nights in Split, we were thinking to use Split as a base for day trips. We no longer enjoy multiple moves with luggage etc. Could Vis be a day trip from Split, with lunch?

A lot depends on your feeling about boat trips. On the one hand, they are scenic. OTOH, they can be long, and they are almost all plied by catamarans these days, not ferries, where you could be out on the deck in the fresh air. (Only some cats provide this option so you are likely to be inside.)
There are day trips to Vis, but I like moving bases versus day trips--it's just a personal preference and I like being in these tiny places when day trippers have departed, enjoying different restaurant choices at night, that kind of thing.
It is also nice to be in one place for nearly a week though!

It’s about a 2-hour ferry ride to Vis from Split, so that’s a lot of time on the water for a day trip. There are closer islands that you could visit but I personally haven’t seen any of them. Perhaps others can recommend.

It’s probably a good idea to taxi from Dubrovnik to Cavtat. The taxi can stop right at your hotel, rather than you having to find the hotel from the bus station with luggage in tow. But if you’re packing light, with just a roll aboard suitcase, and feel adventurous, be aware that the buses stop in a big parking lot and it was a simple matter to just walk over to the Cavtat bus. You just need to know the bus schedule in advance. And directions to your hotel in Cavtat.

Thanks, Charlene. This has been helpful.

Ivan Ćosić (MC-Travel Croatia) does private transfers in this area. Hes a local experienced guy and I highly recommend him. He also does scenic stops in Ston, where you can also enjoy a boat ride with oyster tasting.

The drive itself is beautiful, and with stops like this, it becomes a highlight of the trip.

Highly recommended for a laid-back, scenic day between destinations.

Thank you Johny. Private transfer was actually our first choice. It becomes rather costly for only 2 people. I will see if I can get a qote from him.