Need feedback on 16 day itinerary

I haven't been to Ribe, but going there after Aarhus doesn't make sense to me. There is another ferry that goes in the direction of Ribe from Aero, so you don't have to go back through Odense.
If you're going to get a car, I would probably get it in Odense, returning it in Aarhus if the drop-off fee isn't outrageous. I would add a night or two to Aarhus. Lots to see and do there. Or bypass Copenhagen on the way back and head straight to Malmo and stay two nights there.

Is this itinerary AI generated? Phrases like "if you want nature" suggest someone else prepared it. Also, this would explain that zig zag of Aero-Aarhus-Ribe.

Yes, I guess I've been busted. The itinerary was indeed AI generated. Sorry about that, but I've found the whole process of putting together an itinerary pretty daunting, so I thought I'd give AI a try. I thought it looked pretty good, which is why I posted it here. My apologies if this was a faux pas. As a poster, however, I am absolutely legit. And I definitely appreciate your help.

I love the suggestion of going to Ribe before Aarhus. That makes sense to me. I'm having second thoughts about Malmo, though. I've read in some places that it's not that safe, so maybe not the best idea?

Please continue to offer suggestions, though. I can use all the help I can get.

There's nothing wrong with using AI to generate an itinerary, but as the previous comment mentions, check for common sense. If you're not comfortable with Malmo, maybe Stockholm? There's certainly plenty to see in Denmark. It's pretty far north, but take a look at Skagen and Grenen.

I also think AI can be a good tool for planning such a trip, but as always with AI, keep an eye out for its limitations. Overall it has provided you with a pretty decent itinerary. There’s a good amount of variety, and while you don’t see everything, you do see a lot.

Ribe is a nice and historic small town, and I have never regretted a day spent there. Consider visiting Vadehavscentret when you’re in Ribe/Wadden Sea.

A car for day 7-12 is not a must for the most part, but may still be a nice to have, as it also makes it easier to stop at attractions along the way (e.g. Koldinghus, Jellingstenene, and such). You only visit towns and cities that can easily be reached by rail (or ferry). But for the Wadden Sea you really should have a car, as bus service in this (relatively sparsely populated) will be lacking for a Wadden Sea day. On Ærø a car may be nice if you want to leave Ærøskøbing, but they do have an hourly bus service on the island (until around 8 or 9 PM). But you don’t need a car for all of day 7-12 (and I see no reason to have a rental car while in Aarhus).

I also agree Aarhus could use another day, it’s a lovely city. Also consider adding Moesgaard Museum to your itinerary in Aarhus.

If it was me, I’d probably like the free day a bit earlier on the itinerary, to have it as a cushion to avoid exhaustion towards the end of the trip.

There are mixed opinions on Christiania. If you are reading more about it, keep in mind the illegal drug trade on Pusher Street was cleared out last year. Obviously that has an effect on the community. If Christiania isn’t for you, Christianshavn (the part of Copenhagen where Christiania is located in) can be worth a stop anyway, so your time won’t be wasted. The Church of Our Saviour is on Christianshavn too, anyway. Walk along the canal of Ovengaden, I’d say it’s quintessentially Christianshavn.

I have also read the headlines of shootings and other serious crimes in Sweden, and while unsettling to read, I have never experienced any unsafe situations during my many visits to Sweden through the years (that includes recent years). Sweden is still a safe country to visit, just like Denmark and many other countries (thankfully). I’m not in Malmö that often, but note articles you may have seen are mostly about events that take place in areas you will not be going to as a tourist anyway. That being said, Lund is great too, and you can visit both Malmö and Lund on the same day.

Finally, in case you aren’t aware yet: In May 2025, the 14th, 24th and 25th are public holidays in Denmark. Most retail stores will be closed on these days, but you can expect most sights, attractions, cafés, restaurants, etc. to be open as usual.

I have friends and family in the Malmö region and visit often. A day trip to central Malmö and the places you mention is not something I’d worry too much about. As for the itinerary suggestions, in my opinion the castle is not really a must see, especially compared to the others on your list in Denmark. If you go to the waterfront/Turning Torso area, have lunch at the Malmö Saluhall (food hall). And get a cinnamon or cardamom bun at St Jakobs stenugnsbageri. Malmö itself is not really packed with “sights” but has some interesting and quirky local shops and lots of good restaurants, at much more affordable prices than Denmark. As mentioned, the university/cathedral city of Lund is a good alternative (cathedral, Kulturen open air museum) or could be combined with Malmö.
Also, day 4 looks a bit tight to me - 2 castles in one day might be a bit much. They are both worth visiting, just don’t know if I’d do them on the same day. Helsingør also has a good maritime museum and you can easily spend a full day in the area. If you have extra time in Copenhagen and the weather is nice, you could also look at visiting the old fishing village of Dragør.