Yes, not bothered to list any of the sites within Busan but the Jigalchi fish market and other markets are high on the list, and have a long list of other things I'd like to see so will need to narrow down. Drawn to the cable car as one activity!

Thanks, I'm hopeful the tourist office can help me with getting this kind of information about accommodation options and accessibility for templestays.

Thanks, the more I looked the more I knew I could squeeze it in but would be more enjoyable with the extra night.

I'm struggling more on this one. I'm not sure Buyeo calls to me as strongly as other sites, whereas Suwon is a must see. I didn't find as much drawing me to Daejeon so thought perhaps a single night in Suwon might make sense. Still thinking on this bit, it hasn't clarified in my head yet at all!

I am looking at Icheon (pottery village) rather than Incheon where the airport is...
I have a lot down to explore in Seoul, so figured might be easier to do it as part of the post-Seoul self-drive segment, though I'm not wedded to that.
Another option is to visit it on the way back from Gyeongju to Seoul.
Another option is to extend Seoul to 6 nights in that original block and include Icheon as a day trip, as you say.

Thanks again for helping me bounce ideas and options! So helpful, really appreciate it!

I haven't been to Suwon, but I hear there is a museum there devoted to Nam June Paik, if you are interested in modern art.....

Oooh I'd not come across this artist but just had a google and his work looks really intriguing, thank you!
Looks like it's closest to the Korean Folk Village!

Always a pleasure to help someone plan a trip to special places!

A few notes about food. You should seek out sujebi (hand torn noodles), kalguksu (knife cut noodles) and kongguksu (noodles in a cold soy milk broth). I don't have specific recommendations for you. You might find many versions of kalguksu, but the default is often with chopped manila clams. Sometimes this will not be mentioned on a menu, they just come in the bowl anyway. Subtle flavor. When done right can be astounding.

The first four links here are from an old Visit Seoul program called Food Tours with Haechi, a photo journey for the internet. There are total of 20 tours, but I can only find 5 of them anymore. Interesting reading.

I highly recommend going to the next place in Busan for their pot of giant mandu.

And finally, in Seoul I recommend having the Maneul Garlic Fried Chicken. We also ordered the "chrysalis" on the menu (yes, there is English on this menu), so if you are open to the idea of ordering larvae, then this is the place to do that. The chicken comes with a crazy amount of garlic sauce. Adding it to the chrysalis makes it wonderful.

Jokbal Alley

Photo Walk In Korea: FOOD TRIP TIPS FROM HAECHI EPISODE 3: Jangchung-dong's Jokbal Alley

Gwangjang Market

https://seoulladies.wordpress.com/tag/haechi/

Namdaemun Market

Namdaemun Market's Galchi Jorim Alley & Kalguksu Alley | Korea in World

Ganjang Gejang Alley

Sinsa-dong's Ganjang Gejang Alley | Korea in World

TTeokbokki Town

https://english.visitseoul.net/other...ki-Town_/32633

Giant Mandu in Busan:

지심정
Ji Sim Jeong
부산광역시 수영구 광안2동 남천바다로 35
35 Namcheonbada-ro, Gwangan 2(i)-dong, Suyeong-gu, Busan, South Korea

https://cimg8.ibsrv.net/gimg/www.fod...36031c6d02.jpg

Maneul Garlic Chicken in Seoul:

Daelim Wonjo Maneul Tongdak
73-10 Guro 4(sa)-dong, Guro-gu, Seoul, South Korea

대림원조마늘통닭
서울특별시 구로구 구로4동 73-10

https://cimg4.ibsrv.net/gimg/www.fod...7d215ec6b3.jpg

Lastly....

Here is my Trip Report in case you haven't stumbled across it yet.

https://www.fodors.com/community/asi...korea-1026725/

Thanks to the contributors to this thread. I've spent quite a lot of time in Asia but never to South Korea. I'm finding the information very intriguing.

Just found out about Mr Toilet House (now a toilet museum) in Suwon and yeah I'm going to HAVE to go to that!!!!

The public toilets in Suwon are quite spectacular! Whether you visit the museum or not, I would encourage you to visit one or more of the public toilets if you do, indeed, go to Suwon.

This definitely tickles my amusement bone!😁

Just booked my internal flight from Jeju to Busan, leaving Jeju 8.45 am and getting into Busan 9.45 am.
I went for Korea Air as the booking can be cancelled/ refunded (minus a charge of I think 5000 per person, which is nothing). Plus this airline also allows 20 kg cargo baggage, plus hand luggage, whereas the budget airlines don't.

On car rental, I'm trying to work out the various bookings.
I'll need either one rental from Seoul to Jeju City (so drop off in different location, and not on the mainland to boot), or split that to Seoul to Mopko and Jeju City to Jeju City
And I'll need another then from Busan to wherever we decide to drop, either back in Seoul or in Gyeongju... or elsewhere.

I did look at getting one single car rental and taking the ferry from Jeju to Busan but that's such a slow option, comparatively, I am not sure I want to lose a half day extra.

Sounds complicated, but it looks like you have your options. I'd be interested to hear how you wind up solving this question. You could treat the Jeju portion of the trip as a separate entity, flying RT from Seoul, leaving intact your mainland car trip. I didn't have as much time as you do, so I chose a different island for the coastal scenery. BTW, Busan has a dramatic coastal walk at Yeongdo Lighthouse....

Thanks, I did look at that but the itinerary didn't click for me that way...
I have the lighthouse walk in my notes, good to know it's worth visiting, thank you!