Every bride should protect the investment she has made in her wedding gown and have it professionally cleaned and then stored.  A dry cleaner that specializes in preserving wedding gowns can make sure that your wedding gown (which may be an heirloom one day) will be protected from any type of soiling and aging so that it will look brand new.  When you pull it out in 20 years for your daughter to use, you want it to look just as it did on the day you wore it.   

It is very common for a bride to "preserve" her gown only to find out, years later, that the dress has turned colors because it was not cleaned or preserved properly.  Spills are death to a dress.  Body oils and perfumes can turn the fabric yellow.  If a dress is not properly cleaned prior to being stored, any unseen stains (like champagne that you can't see) will show up on the dress an possibly even damage the fabric.  On top of that, if the dress and/or fabric is not super high quality, it may even come apart if you attempt to dry clean it after the fact.  

Now, with all that being said, many brides will not choose to pack their gown away in a box.  Many will want to have it altered and wear it again.  Of course, this is perfectly acceptable as well.  However, the dress should still be professionally cleaned within 1-6 months after the wedding to help preserve its beauty.  Those unseen stains will definitely turn the fabric after a few months.  

The same will hold true for your bridesmaids.  If they intend to wear their bridesmaids dresses in the future, they will want to have them professionally dry cleaned shortly after the wedding.  This way they will be able to get much more use from their dresses.  

Here are a few more tips:

• Be sure to find a cleaner that specializes in wedding dresses.  Ask if a different solvent will be used on the gown than is used on regular clothes.  Many of the standard solvents are entirely too harsh for a wedding gown.  Most gowns need to be cleaned in an acid-free environment with the most gentle cleaners possible.  
• Be sure to take a look at your dress before it is packed away.  This way you will be able to see for yourself if there are any stains that should be removed prior to storage of the dress.
• Acid free tissue should be used between the folds and stuffed into the bodice and skirt to prevent the gown from developing permanent wrinkles.  it will also help to stabilize the entire environment of the box.
• Anything made of foam such as perspiration shields or shoulder pads should be removed from the gown before storage.  Foam does not have a good shelf life and when they begin to deteriorate could ruin the entire dress.
• Do not pack your gown with any plastic or metal.  Definitely do not pack you wedding dress with mothball or crystals.  The chemicals in these products can ruin the fabric in your dress over time.  
• Do not hang your wedding dress for a long period of time.  If you intend to wear it frequently, then it can be hung.  However, if you will be putting it away for long term storage, it should be in a box which is not completely sealed.  The dress actually needs a bit of air circulation.  Once it is cleaned and stored in a box, you can put it under the bed or in a closet.  
• Don't put your gown in the attic or basement.  The extreme temperatures can damage the gown as well.  
• Take your gown out periodically and check it.  Just be sure to wear white gloves while handling it as oils from your hands can leave unseen stains.  Also be sure to repack the dress with plenty of acid free tissue to prevent any permanent creases in the fabric.
• Professional cleaning can run anywhere from $75 all the way up to $600 or so.  This will depend on the size of the gown, any details and if there are any difficult stains.  
• You can save a bit of money and pack the gown yourself.  However, you will still need to have it professionally dry cleaned first.  You can use a large box or a cedar chest.  Be sure to use lots of acid free tissue paper to stuff the bodice and skirt and also use it between any fold to prevent permanent creasing.  DO NO use plastic or brown boxes.  A cotton liner in your box will be very helpful. 

Your wedding gown is probably the most meaningful dress you will ever own.  Whether you want to keep it as a memento or pass it on to your daughter, it deserves this special attention.  If you clean and store your gown properly it will last your lifetime and more.