If you like pierogis, I highly recommend checking out the S&D polish deli in the Strip District. They have some different flavor choices (i.e. Cheese, potato, etc) and other homemade traditional polish food (i.e.: pigs in a blanket) which can be ordered for eating in, takeout or even purchased to cook at home. Food can be ordered and paid for and then brought out when it is ready.
We were here on a weekend and while it was busy, we were able to get a table. The interior is like a small store/market with a small area with some tables to eat. Service was friendly and pretty quick too. Think in between fast food service and sit down meal. Restroom was available with a key for customers. Prices also very reasonable.
I will definitely be back to get some delicious pierogis from S&D again!