Whether to get a mattress and box spring or a mattress with slats is a question that arises for many a prospective mattress buyer.
Both have their benefits and both have their shortcomings. Which one you chose ultimately comes down to which features are more important to you.
Extends The Life Of Your Mattress: The biggest credential of a box spring is that it acts as a shock absorber for your mattress. The extra give reduces wear and tear on the mattress and prevents it sagging prematurely.
Slats on the other hand have much less give than a box spring and without the extra support reduce the life of the mattress. Given that a mattress should be at least a once every ten year purchase, and that it is a high cost product, anything that extends the life of the mattress should be seen as beneficial.
Bouncing On The Mattress: The other key factor if you have children that like to bounce on your bed is the extra give from a box spring. A lot of bouncing on a surface with little give such as slats will wear out the springs in your mattress a lot faster.
Do You Need A Shock Absorber?: To counter the argument of box springs as a shock absorber is to ask where do you draw the line?
If a mattress acts as a shock absorber to the body and a box spring as a shock absorber for the mattress, what acts as a shock absorber to the box spring?
Another box spring? Where do you draw the line? Do you need five mattresses and five box springs on top of each other to be comfortable?
I would still argue that the line is well drawn at a mattress and box spring. But some people happily draw the line at the mattress alone and say that the box spring is superfluous. In that case they get slats, a solid wood foundation or put the mattress on the floor. It is personal choice.
Aesthetics: Slat beds have a more stylish modern look than box spring beds and this can be a contributing factor in many people's decision to go with them.
Storage Space: You cannot store anything under the bed when you have a box spring but you can with a slat bed. If you are pressed for space in your bedroom or home then a slat bed can be very useful at freeing up much needed storage room.
Slats Are Cheaper: The fact that slats are cheaper than box springs means that you can spend more money on the actual mattress itself or just save the money. To counter that though is the extended life gained by a box spring. You may get a better mattress for your budget but if you get less life out of it you lose money in the long run and the long term value is not as good. Nevertheless slats are cheaper and this is a key benefit.
Better Air Circulation: The underside of a mattress on a box spring does not get any airflow to it. A mattress on a slat bed does. This helps keep out moisture mold and mildew and prevents nasty odors forming.
The fact that there are five arguments for slats and only two for box springs would suggest that slats are the better option. However the fact that a box spring extends the life of your mattress is a much more powerful argument.
This factor alone should have you tending towards a mattress and box spring. My suggestion is that the box spring be your default option and you only choose slats if you have a specific and pressing need to go that way e.g. you desperately need the storage space.