This study examines the optimal viewing positions and the effects of viewing angles on menu navigation layout design for large-screen interfaces. Using a 7 × 2 m2 display, experiments evaluated viewing distance (2H, 2.5H, 3H), viewing angle (0°, ±15°, ±30°, ±45°, ±60°), and eight menu layouts. Results revealed that a viewing distance of 2.5H to 3H and angles within ±45° offered the best user experience, visual comfort, and lower task difficulty, with viewing angle having a greater impact than distance. Central menu layouts consistently resulted in the shortest response times (RT), while side menus had longer RT, with left-side menus outperforming right-side menus at +30° and +45° angles, though the opposite was observed at −45°. As viewing angles deviated further from the center, task performance decreased, particularly for side menus. Interaction effects showed that layout and viewing angle significantly influenced task efficiency and user experience. These findings highlight the importance of optimizing viewing distance, viewing angle, and menu layout for large-screen design, with centralized menus and angles within ±45° being ideal for usability and performance. This research offers valuable guidance for improving user experience in smart city applications.