I have been involved with the internal arts primarily Yang Tai Chi Chuan but also Ba Qua Chang and Hsing-I Chuan for twenty plus years. Just like the hard systems the internal systems can be grouped into their combat strategies. Hsing-I Chuan is "attack the attacker". Ba Qua Chang is "avoid, absorb, and redirect the energy to the attacker. Tai Chi Chuan is both, especially the Chen system of Tai Chi Chuan.
Hsing-I Chuan is more for younger people as it involves accelerating past the target (the Attacker). It is like imagining a black hole sucking you into it passed the attacker. The attacker is not important. This system is tough on the joints especially the knees and ankles. Movements are done accelerated.
Ba Qua Chang is the escape art and relies on flexibility. People in their thirties to sixties can do this art. Movements are usually medium to fast. Applications to the movement are hard to decipher without a skilled instructor.
Tai Chi Chuan is linear and circular, fast and slow. Movements are easier to decipher as far as applications. The beginning students go through the slow meditative forms first for the development of coordinating the breath, body movements, and the mental intent. After that it is medium to fast or as fast as you need to be to nullify the attack.
What I have seen is that most of the Tai Chi Chuan schools teach just the meditative part of this system.
If at all possible investigate the Tum Pai branch of Kajukenbo. One of the reasons for the development of Tum Pai was to have older students still workout in a soft internal system and still be learning a combat orientated system and not some "new age" type of martial exercise. Tai Chi Chuan is a Martial Science that is in the Combat Mind Set. The health, mental development is the side product not the main objective. Tai Chi Chuan can be done until you are mentally or physically incapacitated.