May 14, 2015 is your final chance to create standard awards by combining, for example, 18900 points with a 0.25 credit "seed". On May 15 Southwest will convert your seed credit to points, at 1200 points per credit.
Standard awards are useful primarily for last-minute travel such as family emergencies. In those cases fares are high yet some flights are lightly loaded. Southwest is often willing to give you a standard award seat on one of those off-peak flights, even across the country.
Any flight with a cash price of $175 or more each way is a good candidate for using a standard award. If you buy such flights regularly, you should consider creating standard awards using your seed credit(s) if you and your family members have them.
For more discussion, see
http://www.flyertalk.com/forum/south...14-2015-a.html
I continue to believe that Southwest would benefit from offering flat rate last-minute redemption on lightly loaded flights. For one thing, Southwest's new floating redemption rate policy would accommodate this easily. For another, this capability exists in competitors' programs, albeit carrying a late booking fee for non-elites.