How Long for Tottori Sand Dunes?

For my next trip to Japan, I am planning a stopover in Tottori, either en route from Osaka to Kinosaki Onsen, or as a day trip from the latter. I am mainly interested in visiting, obviously, the sand dunes, but the infrequent trains to and from Tottori have me concerned. How long do you recommend would be enough time to fully enjoy the dunes and the nearby Sand Museum?

Side question: I have also been interested in joining a sandboarding class at the dunes, but that takes up a big chunk of time (1-3 PM). Is it a worthwhile experience, especially for those who speak limited Japanese?

One full day is enough but there are other nice places in the area so a couple of nights is worthwhile if you have time.

As mentioned above, I will be staying in Kinosaki Onsen instead, and have already booked my hotels. At least for now, actually staying over in Tottori itself is not in the plans.

Personally, I think visiting the dunes would be better if you are in the area compared to going a far way out.

They look ok - but the area is not that big or impressive. There are much more impressive dunes in other locations outside of Japan. For me - I thought the Sand Sculpture museum was not interesting than the dunes themselves. Do note that the dunes are quite a distance from the town so will require some time to visit.

Here is my original post when I visited: https://www.japan-guide.com/community/mfedley/report-2244

Sorry, I misread.

It's doable as a day trip, you'll spend at least 5 hours on public transport though.
Depends on how you want to spend the time in Kinosaki.
I thought the museum was incredible and the dunes beautiful, the city itself is very plain but has some great restaurants.

My original post should have read that the dune museum was more interesting than the dunes themselves. The sculptures can be quite impressive

Let me ask you this, then. If I could only pick one, which would be a better choice for a day trip from Kinosaki: Tottori, or Amanohashidate?

I couldn't really answer that tbh, there was the most torrential rain when I was in Amanohashidate.
Ine is lovely though, worth a look too if you're driving.

「Let me ask you this, then. If I could only pick one, which would be a better choice for a day trip from Kinosaki: Tottori, or Amanohashidate?」

Of the two, I think I'd recommend Amanohashidate. While Tottori's sand dunes are nice to look at, a big part of the tourism attention they get is because sand dunes are rare in Japan, not that Tottori's sand dunes themselves are world-class. On the other hand, Amanohashidate is a beautiful view that also feels more unique to Japan.

To be honest - I'd look at what the weather is doing and then make a decision.

Amanohashidate is best when it's a clear day with good visibility. Tottori is also similar weather.

Another option is Izushi which is a small castle town near Kinosaki: https://www.japan-guide.com/community/mfedley/report-2242

I have been to Tottori Sand Dunes many years ago and I spent there only half day, it was a big rush as I did not have lot of time, I remember I started early in the morning dropped lugagge in the station and then went by bus and spent like 3 h for the sand museum and walk the sand dunes and eat something in Sakyu Kaikan and came back to the station and have lunch overall in total maybe I spent 4-5 h from the station. It was a bit rush but I did not have much time.