Square dancing is often a more strenuous exercise accompanied by music, crowds of people of the same age, bright lights and a joyful atmosphere, although there is no practical significance, but the exercise makes people happy.
Elderly people practicing Tai Chi is to cultivate the body, too aging bones and muscles are not suitable for high-speed bouncing, strenuous action alternatives for loosening the tendons and bones, expanding the chest, serene and not generate waves of the state of mind can be effective in less cardiovascular morbidity - Tai Chi is also so slow down.
Overall, if you can still dance square dance on it! If you can't dance, you should consider Tai Chi.