Let me add a few items to Kay2's report on Jeju. I was there in 2008.

There is a Museum of African Art in Seogwipo that is said to be the
best on this topic in all of Asia. It was certainly a revelation to
me: I had not looked at African art before, and found the collection
truly impressive and eye-opening. Furthermore, the building itself is
a reproduction (in concrete) of the great Mud Mosque of Djenne. Most
of us aren't likely to visit the original any time soon, so this is a
bonus.

There are several good waterfalls in the area: Cheonjeyeon (near
Jungmoon/Jungmun), Cheonjiyeon (a bit further out, in Segwipo), and
Jeongbang. The latter is claimed to be the only waterfall in Asia
that lands directly in the ocean. The claim is false (there are
several that do this in the Shiretoko peninsular, for example), but it
is certainly cool to see.

Then there's Jusangjeolli, which is a stretch of cliffs with
spectacular basalt columns (the hexagonal kind, like the Devil's
postpile in California, or the Giant's Causeway in Northern Ireland).
There are plenty of other good scenic spots around this section of
coast, with one called Oedolgae being particularly good.

Guidebooks recommend the Yakcheonsa buddhist temple, but I found it
largely a waste of time: it's a very recent construction, and the 500
figures in one of the lower halls are small and mass-produced. It's a
nice peaceful area, though.

I was traveling solo and didn't visit Loveland, but this might be fun
in the right company (Google it).

Further north (near the Seongsan/Sunrise Crater) is the Manjang Gul
Lava Tube. This is said to be a natural wonder, but it's a long
descent down steps, then a half mile walk underground on unlit uneven
ground, and I gave up (I'm somewhat disabled).

I rented a car for a day to see these places (from the Avis place in the
Hyatt--note that you need an International License to do this), but
the museum and waterfalls/cliffs are all close to Jungmun and taxis
should work. Not much English is spoken, but Japanese sometimes
works in these south eastern parts of Korea.

Overall, I would not make a special trip to Jeju, but there is plenty
to see if you happen to be there anyway (it's a popular place for
conferences, which is what brought me there).

Thank you both for the information. My son visited Jeju and suggested my husband and I might enjoy a trip there when we make our next visit to South Korea to see him. This is the same son who booked us a love motel when we visited him before. Good to hear others opinions of Jeju.

I think I saw a love motel on Jeju if you want to repeat the experience. There was also at least one love/sex museum. In fact, there seemed to be a museum for everything--I saw the African Art Museum mentioned as well as signs for Teddy Bear, Sea Shell, Love/sex,Film, Tea, Ripley's, rock,chocolate as well as provincial art and natural history. Maybe they are popular as air conditioned breaks from the heat/humidity of the natural sites--volcanic craters, lava tubes, beaches--and the golf courses. The unspoilt areas are naturally beautiful and the tourist industry has developed and signed the area to make sure you can find whatever you want to spend your money on. The developments reminded me of the touristy strips along Florida beaches while the interior was relatively unspoilt.

My son said the Korean government is trying to promote foreigners purchasing condos on Jeju by relaxing some of the rules governing non citizens buying property in Korea. Not sure I am ready for a vacation place there!