As someone above mentioned Torun and Malbork should be obligatory :)
Both very interisitng.
But don't forget about the east side of the country, some hilighsts are on the list given above:
-Bialowieza National Park
-Zamosc - A UNESCO-listed small town in the east of the country with renaissance-style architecture.
-Kazimierz Dolny - a really small but beautiful city, with great atmosphere, esp. in low season.
Have fun :)
mommyk5
You don't have to speak Polish to come here on your own.
I don't speak khmer or thai, but I visited both countries :)
You will encounter some problems, but your travel will be even more intersting :)
Really, lots of people do speak English in Poland.. You can always ask for help.
It's a good idea to go to Poland (or anywhere you don't speak the language) with one of those slim language travel books and a Polish-English dictionary. After that, you should be good to go anywhere you like. No need to be a Polish speaker or for them to understand English. You will get by just fine.
Personally, I wouldn't be so pre-occupied with seeing 'all the highlights' whatever that means. If you just galavant from city to city, you'll never really visit the countryside. I spent three weeks only in Malopolska, so it is possible to stick with micro-regional highlights. The wooden churches (there are dozens), especially the one at Debno, were a highlight for me, and that is not going to fit into an easy list, though it is a UNESCO World Heritage site. Silesia has a great national park site near the Czech border, the Gor Stolowych National park, with its unusual rock labyriths, Biende Skala and Szczeliniec Wielki.

" I tend to be more of a city person who like to visit galleries and museums."
My suggestion:
4 nights- Warsaw>>>4 nights Krakow (inc Auschwitz, Salt Mines)>>1 night Czestochowa>>2 nights Wroclaw>>2 nights Poznan (inc Gniezno, Museum of the Beginning of the Polish State, Biskupin Iron Age Village)>>2 nights Torun (inc walled town Chelmno)>>4 nights Gdansk (inc Sopot.Oliwa, Malbork)>> 1 night Warsaw, for departure or depart from Gdansk. Take train (2nd class ok) or bus, based on travel duration or time of departure or number of connections.

Mommy5k - don't worry, you really don't need to speak Polish. I guess majority of younger people here speak at least basic english and people are very helpful. Buy a pocket English-Polish dictionary, LP guidebook and it will be OK. It's also good idea to have a small notepad always with you - you can write down address, departure time etc. which is very useful when buying rail or bus tickets. It's much easier to show such note than trying to pronounce it in Polish ;-)

Hi,
I've only been to Poznan, but from what I've heard the main place for sight seeing is Krakow and other cities have a few things to see which can be done in one day.
I think that Poland is best as a place for going to bars and having fun. In Poznan I found the bars to be amazing, it's so friendly and really good fun to have a drink with the locals so I'd make sure that you experience the night life there.
To be honest Poznan didn't really have anything attractive to see apart from an old town that can be seen in two hours. It also had a nice shopping centre, but apart from that it was more of a place for going out.
I don't speak a word of Polish, but in Poznan I had no trouble at all communicating. A lot of people will at least speak a little bit of English and some people will be fluent.
Chris.
Go to Krakow, Auschwitz and zakopane, you'll have a perfect mix of city, shopping, culture, war, nature and of course good food & drinks (try in Zakopane the warm beer with herbs&honey).

If you travel from Warsaw to Cracov, you can visit
http://en.wikipedia.org/wiki/Jaskinia_Raj
nearby Kielce, which is along both the railway and the highway between the cities, so it wouldn't waste you too much time (it is not big as well), while it is one of the most beautiful caves I've ever seen , and judging by the pictures of numerous 'the most amazing caves in the world' , it has a pretty unique display os stalactites and stalagmites. I'm not implying it is a world wonder, but something that won't take you much time and will be nice.
Here's a picture:
http://swietokrzyskie.travel/data/mp/_tapety_1600/1916/jaskinia_raj_1600x1200.jpg
Edited by: lajtu