Cities you've visited that were unexpectedly great
 

Cleveland. We've been three or four times now. It's an easy drive from Toronto. It has a beautiful and lively downtown core, a good baseball stadium, great restaurants (including a charming Mexican restaurant off the beaten track where I saw my first fireflies ever!), a wonderful art gallery and of course, the Rock and Roll Hall of Fame. Oh, and a tremendous market.

Athens. I went to Greece grudgingly as it was on my DH’s bucket list. I unexpectedly loved it and would have happily stayed longer.

Madrid

Buenos Aires

"Great" may be going out on a limb. Eye of the beholder and all. But I really enjoyed both Budapest and Phnom Penh much more than I expected. And more than some places I've looked forward to. Boulder made such an impression years ago that if I were to move back to the US, I would probably live there.

Not a city, but going over the Andes in a bus from Mendoza, Argentina to Santiago, Chile. I was so exhausted from the late nights, wine, salty food. I just wanted to take our flight to Santiago. A few in our group wanted to take the bus, so we did. Eight hours but it was the highlight of the trip. So fun and great memories!

Georgetown on the island of Penang, Malaysia. Interesting mix of modern, British colonial, Chinese houses, mosques. Loved the food, especially the hawker stalls. Drinking a cold beer while watching the spectacular sunset was amazing.

St Augustine, Fl. History, museums and a lively (if touristy) downtown. Unfortunately it is in fascist Florida, so don't visit.

Veracruz, Mexico. Hot, steamy, gritty port city. So much that made Mexico what it is today (for better or for worse) came through Veracruz. A culture unique to the rest of the country.

Nairobi

Some interesting responses above. CG, Bourdain apparently favoured Georgetown big time. For us, keeping the 'unexpectedly great' aspect in mind: Lyon and Vancouver (aka Raincouver).
Cathies, once I finish up posting the conclusion to our foto essay 'Passage to China', it is my intent to post a similar TR cum foto essay for Athens, plus some Greek Isles.
I am done. the urban

Ferrara

z, Lyon and Strasbourg are two cities in our plans for next year when we travel to Paris.

Lille, France

I'm not really sure that I understand this question. Why would you spend your holiday time visiting a particular city unless you expected it to be good? I don't get enough holiday time to visit places unless I expect to enjoy them.

Go back and look at my original post. I didn't ask 'where have you been on holiday that you liked more than you expected'.
There are lots of other reasons one might visit a city other than being on holiday. You might go on a business trip, to visit family, for a special occasion like a wedding or funeral, or to visit one particular landmark or attend an event. You may have had no other interest in that city but then find out you really liked it a lot and wanted to return for a holiday.
For example, we first went to Cleveland for no other reason than to visit the R&R Hall of Fame but on that visit we really liked the city so we went back several times and explored more of the city each time.
But it could also work even when you're on holiday. When we were in Bologna we took a day trip to Perugia just because we could do it easily. Perugia has never really been on my list of places I'd like to visit but now that I've been there for just part of a day, I wouldn't mind going back for a longer visit.

I'd like to go to Lyon next time we're in France. We missed our chance for a house swap when we had friends who lived there but now they've moved.
Dagnabit!

dreamon, I just thought of another perfect example of this.
During our stay in London, one of our excursions was to Hamburg, Germany, where my SO was attending a conference and I tagged along. I really expected Hamburg to be either largely industrial or largely quaint but boy, was I ever surprised! It's a beautiful and sophisticated city with a main street that would rival Fifth Avenue!
Definitely 'unexpectedly great'!

OK, I promise this is my last example of this.
We were vacationing somewhere in Florida, probably Fort Lauderdale, and we decided to drive up to Delray Beach to go to a blues bar a friend had recommended. We'd never even heard of Delray Beach before, never mind have plans to visit there. Anyway, we went up for the evening but were early enough to take a walk on the lively main street, fell in love with the place and that's where our Florida vacations have been ever since.

Lima, Peru. Everyone used to post about how awful and unsafe it was. Turned out to be a favorite. I went so often I learned how to use the unofficial minibuses to get around, and my stomach apparently aquired the local gut flora so was able to eat nearly anywhere without upset. (The only place that I think gave me something was a trendy place but you can never be sure). Great museums, great food, great people. And it's cool during our summer. Went back many times since it's the gateway airport into Peru. I was able to give some tips for a tour guide that we met on a Cape Horn cruise and he used them for his lecture on his final repo cruise back from Santiago to Los Angeles.

Lyon has a fabulous weekend market @quai St. Antoine. Also, happy to provide contact info for the Lyon couple who rented to us in the Old Town. Atmospheric location literally within the 'miraboule' (traboule) called 'La Tour Rose'.
I am done. the unexpected