Krakow 
I LOVED Krakow. Where do I begin....we stayed in a private room at the Greg and Tom Hostel. It was only $120 for three nights with Breakfast and Dinner included! The room was really nice--minus the curtains, it was a room out of the Ikea catalogue. There are three different Greg and Tom hostels, all walking distance to the train/downtown, but they have very different vibes... so be sure to double check which one will suite you best.
Small deck off the kitchen.
Pierogis...so many pierogis. The food is so affordable and there is a 24 hour Pierogi and kebab place.. which led to us eating.. A LOT.
In the square there was a HUGE festival with crafts, art, music and food. We went there everyday and I had my fill of sweet waffles and Adam devoured the savory meat plates.
Meat for days....
The city of Krakow is relatively small, making it easy to walk around and soak up the culture. From castles, to amazing food, market squares, gardens, and more, you will enjoy every second.
Salt Mines--A Must Do while in Poland
We booked the tour same day, so no need to book far in advance. It is the only museum where you can lick the walls...and it is SO cool. First, you do have to walk down a lot of stairs.. so have your Fitbit on. You will be 450 feet underground.
The oldest part of the mine was from 1280. It was a huge underground city filled with cathedrals, cafes, a spa, and even a venue for parties! Everything is made out of salt!
Warsaw
We took the train from Krakow to Warsaw. The trains here make the commuter rail in Boston look like a joke! The seats recline, have trays, individual lights and they come around to serve you coffee. Our first stop was downtown.
Warsaw was quite a bit larger than Krakow and we did have to take an Uber to get to the park and Museum area.
It was well worth it. The parks were so beautiful. Filled with tulip gardens, fountains, colorful ducks and hidden art museums.
Not to mention, amazing views...
Funky tree branches...
and people dressed just like you and I.
We stopped to eat at a local bar, and the decor was quite odd, there must have been hundreds of watches all over the walls. Nevertheless, the locals were very hospitable. Everyone we encountered was genuinely helpful and kind, and not to mention, look what $15 can get you.
If you're wondering how many pierogis I ate over the course of the trip, probably around 50. It is safe to say I turned into a PierYOGI. ;)
Our last stop of the day was this Art Museum. Besides the awesome cafe, the museum was quite...imaginative. I can't even put to words the exhibits that I saw and heard. I guess you will just have to go for yourself!
TakeAways
Stay at the Greg and Tom Hostel--free breakfast and Dinner
You will overload on Pierogis
Beautiful and lively City Squares
Festival of food, arts, and crafts
Everything, including fancy dinners, are VERY affordable
Make reservations if you want to go out to one of those fancy dinners
Visit the salt mine with a tour group--no need to book far in advance
Visit Auschwitz either with a tour group, or you can book tickets for free on the website and go on your own. Do this far in advance as you can only enter on your own before 10am. That is what we did and to get there, you just book a bus ticket from Krakow station.
Be present and soak up the what the cities have to offer
Norwegian Air was surprisingly very comfortable and they have 8 bathrooms on board-yay. They also have adjustable dim settings on the windows--it was pretty neat. We did not pick seats in advance nor did we check a bag, so the tickets were VERY cheap.