The Hussain-Doshi Gufa is a modern art gallery within an interesting architectural setting.  It's a collaboration between a leading architect (Doshi) and an artist (Hussain).  The "caves" are art in themselves, but also associated with a gallery, which hosts exhibitions and movies.  You can see the caves in 5 minutes and could savor the experience it for 15-30 minutes.  You can picnic outside also. If there gallery is open, that would be much better.

The site may have a website with current exhibition schedules.  In late December, gallery hours were 4pm to 10pm with documentary movies at 6pm.   These were advertised in posters outside the entrance.   Just a short walk from the Gufa is the campus of the Ahmedabad Institute of Design, which has little art galleries and studios for students that were open to visitors.