I would like to change my style from "poverty chic" to something a little more suitable for my age. I have always had a mattress on top of a box spring on top of a cheap metal frame. If I get a platform bed, can I toss the box spring and put the mattress directly on the bed?

It helps prevent the mattress from collapsing on itself/taking a set...without a box spring you can expect a mattress to only last a few years.

I know this, because I did exactily what you're saying, and I just had to replace my mattress...this time, WITH a box spring Hopefully it lasts more than a few years now...

Just get a bedframe with a well deep enough to hide the box spring...

I have posted this before, but we need a matress forum  

box spring and mattress on the floor and build a "frame" to cover the box spring.

If anything a box spring will help a mattress degrade figure it out  - a plain piece of plywood would be best

Platform beds use either plywood, or several thin planks that have some give. I think the latter is better.

I use a futon on a futon platform bed.  The slats are spruce (roughly 1x2's) and you can either get them spaced 2 inches apart, or a continual set of them, like having complete spruce planking.  I have them spaced apart, I should have upgraded to the continual slats. Spruce has good flex to it.  I got mine from platformbeds.com.  I think with that setup you don't need a box spring.    



I get the Otis brand futons from futonplanet.com.  I usually like them pretty firm and they have lots of options there.  I've never been happy with a standard mattress for the prices they sell for.






 

Box springs are like shock absorbers for fat chicks.

RTFM

My new mattress came with suggestions on supporting the mattresses for best comfort and longest service life. Matched box spring is best, followed by slats spaced no further than 2"

Have you looked at "box springs" lately? Most have zero springs in them. Simply a wooden frame with some fabric stapled to them. Many many years ago box springs actually had springs. Your mattress will be just fine on a price of plywood or slats.