Poland - 5 days in Krakow, which includes 1 day in Auschwitz and 1 day at the salt mine
Croatia - Dubrovnik and possibly 1 day in the Bay of Kotor
Austria - Vienna and Saltsburg OR Vienna and the Julian Alps in Slovenia
Great locations, but you only have a week?
Friday to Krakow, Arrive on Saturday
Sunday - Krakow
Monday - Krakow
Tuesday - There are direct discount flights from Krakow to Vienna for under $100 and about 1 hour of flight time
Wednesday - Vienna
Thursday - Vienna
Friday - There are direct discount flights from Vienna to Dubrovnik for under $100 and about 1.5 hours of flight time.
Saturday - Dubrovnik
Sunday - Dubrovnik
Monday - Return home.
You really need two more days to make that somewhat realistic. If you can leave on Friday and return on Monday, then maybe..... Still, as mentioned, a concentration camp isnt the greatest place for kids.
Much easier would be to skip Krakow and add a day each to Vienna and Dubrovnik. But Dubrovnik is bloody miserable in the summer. Wall to wall tourists.
Think about something a bit easier and less touristy.
Saturday - Fly out, Sunday - Arrive Budapest.
Monday - Budapest
Tuesday - Budapest
Wednesday - there are discount airlines between Budapest and Podgorica non stop, under $100 and take about 1.5 hours, then transfer to Budva. Beaches, walled fortress town, lots to do, fewer tourists.
Thursday - Budva
Friday - Budva with a day trip to a number of great coastal towns or the Bay of Kotor or into the mountains
Sunday - return home
If you can stretch it a day or two, add time to Budapest.