The first choice of all tourists is Kraków, which is one of the oldest cities in Poland.
Absolutely. I personally don't like Krakow that much, but I would still recommend it as first choice to someone visiting Poland for the first time. In most countries, the capital would be the first choice, but Warsaw is mostly ugly, sprawling, unfriendly and increasingly aggressive. However, it is still somewhere you need to visit, if you have the time. Like Milan, the attractions aren't as obvious as they are in Krakow or Rome - so it helps if you know locals or someone who is a regular visitor - which is where we come in on PF ;)
Wroclaw is a wonderful city, by far the friendliest in Poland in my experience, and everything you say about the Ostrow Tumski area is true, I loved it there even though it was dull and raining :)
I want to visit Poland but have only 1 week, which cities are nice to visit and what can you do there?
Depends on how you intend on travelling to PL from Holland, I suppose. If you are near a German city, you may be able to fly direct to Gdansk. The reason I say this is that it would make my following suggestion easier, but you could of course work around this if flying to other airports.
One suggestion is this:
1.
Fly to Gdansk. Largest city of the "tri-city" area of Gdansk/Gdynia/Sopot. Has the strangest atmosphere of all the cities I've visited in Poland, due to its obvious German influence (which affects the way that people look as well - I've never seen so many German-looking Polish speakers before :) ). It's no wonder the Germans want the place back, because it's a lovely town. I wish we could swap it for Liverpool, but I digress... :_
Bus 210 takes 30mins to central Gdansk and costs 2.50 PLN (0.60 EUR). Public transport doesn't directly cross the main city centre, but runs to a ring-road around it. The bus drops you off at the main railway station. All the main attractions are 5-15 mins walk from here.
Things to do: Well, other than the obvious restaurants/bars/cafes etc you could head straight for Dlugi Targ, which is where many of the city's nicest buildings are. Walk along the river, take a boat ride along the river to the Westerplatte. Visit Sopot or Gdynia if you like beaches/seaside towns. Find the "monument to the fallen shipyard workers" outside the Gdansk Shipyard entrance, if you're into things which are a bit more political.
The above would probably need 1-2 full days.
2.
Train to Warsaw, stopping off at Malbork to see the castle (the inter-city line runs this way). Arrive in Warsaw. If you decide you'd rather not spend more than a day here, do this: Leave the Central Station and catch the 175 bus towards the terminus (currently Plac Pilsudskiego, but can change according to roadworks), which is 5 minutes walk from the Old Town. this bus also takes you to the airport if necessary (see below). Ticket costs about the same as a ticket in Gdansk does.
You should save at least a few hours for this area, as it's really nice, but on the bus and as in any tourist area, watch out for pickpockets. You may wish to visit the Royal Castle, which is next to the Old Town Square. Then walk along the main street from the Old Town (Krakowskie Przedmiescie) which is a very upmarket and beautiful old street, filled with cafes, bars, lovely old buildings, expensive hotels, and eventually leads to the University.
Carry along this street and eventually you will reach Nowy Swiat, which is where all the beautiful young people hang out (so why I spend so much time there is beyond me, because I am neither beautiful or young, but I dress better than 98% of Poles, so maybe I fit in, lol). From the end of this street, you can catch the same bus (175) towards the Central Station, stopping off to see the Palace Of Culture and the new London/New York-style skyline which is springing up around it. Under the railway/metro stations are kilometres of subways, which contain small shops bars and cafes, which cater for every need, and are one of the last remaining examples of "old-style" Poland in the central business district - see if before it all gets demolished/refurbished in a few years time. You have been warned ;)
This is enough for one day, but there is plenty more to see if you wanted to stay longer. The problem with Warsaw is that everything is spread out, so you either have to travel by bus/tram/metro, or walk long distances. It's also very ugly in between the nice bits, full of grey Brutalist commie architecture, and this is why it isn't a first choice for first-time visitors. But having lived in London for many years, it doesn't bother me too much, but if you come from a small town/village, it must be a big shock :) Watch out for the drunks/beggars anywhere in the centre, but mainly around the central station. Be polite, but firm. They are unlikely to become violent unless abused, but are very annoying and increasing in number.
3.
Fly to Wroclaw. The train journey averages about 6 hours, and flying in Poland is often not much more than a one-way IC ticket in 2nd class. All of Poland's major cities are about 1 hour by plane. Bus from the airport into town cost £2.40 PLN the last time I was there. Apart from the Old Town and its market place, visit the cathedral and Ostrow Tumski (river island), and walk by the river. Plenty of old churches and museums/galleries to visit. I don't know the city particularly well, but I've been there quite a few times, and found the people to be the friendliest in Poland - you can have a really good laugh with people round there, which isn't really something you can say about Warsaw - people are far too serious/overworked/stressed-out up there.
4.
Train to Krakow. Far from my favourite city in Poland, but an absolute must, as it is the
de facto historical/cultural capital, while Warsaw is the political/financial capital, and the difference is obvious. The Old Town, its market place, the Wawel Castle, the Kazimierz district (former Jewish area) and areas around the river are the obvious places to go. Krakow is easily walkable, but trams run everywhere worth going. As above, others may tell you more about the city than I can. That the city is absolutely gorgeous is a fact, but I personally don't feel much for it. Maybe it's just a bit too obviously "touristy" for my liking. But it's somewhere you really need to go, and I've never met anyone who said they hated it there (including me). Plenty of bars/clubs/restaurants/museums to cater for every taste, but I couldn't find decent pierogi (lol).
I've arranged the above for the following reason: if you need to get back to Warsaw to fly back to Holland, it's less than 3 hours by train, whereas from Wroclaw it's 5.5-6.5 hours, and over 5 hours from Gdansk. Additionally, there may be better flight connections from Krakow than from Wroclaw, as the airport is larger and has more destinations. But I'm sure this proposed itinerary may be altered to suit any plans ;)
Hope this helps. This should be possible over 1 week. I'm sure someone will add to this soon though.