Boyen Fortress - It is a rare example of a 19th century Prussian fortification and is one of the best preserved monuments of defensive architecture of the 19th century in Eastern Europe. You can visit this place with a english speaking guide: Marcin, +48 500 209 895
Before you will start visiting a town visit a Tourist Information on Grunwaldzki Square. Open all year long. They speak english and german.
If you are looking a cheap place with good meals it is OMEGA. Near the town centre on Olsztynska street. Open form 6 am to 8 pm. Polish food. In Ekomarina Port you can visit Tawerna Marina. Prices from 20 to 50 zl. Perfectly place with a nice viev on the Niegocin Lake. 7 km from Gizycko in a small village Upalty you can visit KARCZMA STARY MLYN (Old mill restaurant). Lovely polish food. Really interesting place. The best way to get there it is own car, but also taxi.