And welcome to the Polish Forums.
Which cities are a "must-see"?
I would recommend Zakopane and Krakow.
There is a lot more to do and see in Poland, so perhaps if you could tell us what you are interested in, we could better help you get what you want.
I speak a bit of Polish, but probably not enough to get by.....would this be a problem in any particular cities?
In the cities, a lot of people speak English, less in the country.
And if you can speak a little, it will help a lot.
I am open to other suggestions too...
Come here, rent a car or take the train around the country, you do not need to do that ToursofPoland.com thing, but as I said, it all depends on what you would like.
You will have an excellent time, I am sure :)