Well, swimming once a week, my Speedos generally last a good 2+ years.

When I was on the swim team, swimming 5 days a week... our suits would last a few months. We always used the suits that were falling apart, as drag suits. Layer of a few of them up... and you get to work harder in the pool.

The best you can do it just rinse with water when you get home and hang it to dry. Unfortunately, the chlorine breaks down the suits material. Not much you can do about it.

I don't know about other brands, as I only wear Speedo.