time for new suspension?

Hi,

I have an 96 accord and the suspension on her seems to giving way. I've noticed that recently it goes over bumps pretty hard. I would like to know the average life span of the suspension. How often does one need to change it?

Also, should I change it for an original part or can you gurus reccomend others? I mainly use the car to commute, not racing and don't need anything fancy. Just something smooth and reliable.

Any help appreciated.