Because the city was destroyed after WWII, it was pretty much rebuilt from scratch but the government did an amazing job of rebuilding the city the way it must have looked. To be honest, it sort of feels like a movie set because you know all the buildings are new (relatively speaking) but constructed to look old. Also, the city was rebuilt with a very intuitive grid making it fairly simple to navigate when walking around.
Depending on your tastes, you could really do a lot here. Old Town is probably going to be your main stop as you wander around the confines of the old fortification. There, you can visit the royal palace, market square, or ride a horse drawn carriage.
The great thing about Warsaw is that it’s a relatively cheap place to visit. You can easily eat at a restaurant in the biggest tourist trap possible and spend 50PLN including drinks. You probably won’t even spend that much. You’ll see drink specials all over the place and more than your fair share of bachelor parties or basic partiers on the weekends (if you like to wake up early on the weekends, you’ll probably run into a couple people who may still be wandering the streets in a desperate search for their hotel).
I would say try the zapiekanki since it’s a fantastic street food item. For about 12PLN, you get this foot and a half pizza/bread thing that has mushrooms, cheese, and some type of meat (customizable of course). They may even ask if you want to get some type of sauce on it as well. It’s so good and for $4 USD, you can’t beat it. It seems to be all over the place and a fantastic street food.
Another place to try is this donut place called Stara Paczkarnia. I stumbled across this place as I was wandering the royal route and noticed a line of locals ordering from a storefront. I can only describe it as a donut filled with different filling. I ordered what the people in front of me ordered and my guess is they were asking for the freshest donuts available since the one I got was still warm. My only regret is that I didn’t order more than 1 (but you better believe I went back the next day).
Milk bars are also a thing that many try (myself included). This might be one of the more uncomfortable situations I’ve been in since the menu was printed on the wall (no individual menus to just point at), you then had to go the cashier to order (tougher if you can’t read Polish), and then go the window where they serve your food. I knew al the guessing in the world wasn’t going to get me any closer to making heads or tails from the menu so I just went up and asked for a recommendation (well I typed in recommendation on my translator and showed it to her). She pointed at something, I nodded, then paid and got my food. My guess is that it was a fried pork cutlet with mashed potatoes and this cole slaw type of thing. Can’t complain for paying 13 PLN.
Other places to visit are the Polish resistance monument, tomb of the unknown soldier (with the changing of the guard at the top of the hour), and strolling along the river on the weekend. I’d recommend getting to tourist attractions early since they will be full of tour groups and if you really want to get a photo of the royal palace or the mermaid in the market square without fighting other people, get there early.
Final thought. The people of Poland (in my experience) are genuinely happy (except for one sour troll I had to deal with) and they seemed to appreciate the fact that I tried to say “please” and “thank you” in my awful Polish. It’s almost like they understood that Polish doesn’t sounds anything like the way it’s spelled so any effort is appreciated. Also, many do speak some form of broken English so you’re never really SOL. There is a warmth to the people here that’s feels genuine and not manufactured. If you’re unsure, just ask and have a little faith. I bet it’ll work out for you.