In kiln operator school we are taught that drying related degrade typically occurs when wood dries from green down to around 35% MC. Most degrade results from stresses caused by drying too quickly.
However, the degrade is not revealed until the wood is below 25%, and the lower the MC% goes the more degrade is revealed.
The benefit of leaving the board thick for drying is that thicker boards dry slower than thinner boards. If you resaw your boards first, theoretically you risk having the two smaller boards dry too quickly (since the moisture does not have as far to go when it dries and it is much more difficult to control the rate of drying).
Presuming that your boards are 4/4, I would leave them full thickness for several months in a cool, dry place (or a warm dry place - the key thing being "dry". If they are 8/4, go ahead and resaw them into 4/4 boards as this is a good thickness for uniform (yet relatively quick) air drying. Check them with a meter, once their core is below 25% you should be able to safely resaw them.
Different species have different safe drying rates, so a species such as eastern red cedar (that dries extremely fast) is probably ok to resaw green, but a species with a slow drying rate (such as oak) would be better to dry first and then resaw.
Like Jimmy, I'm curious though as to what the experience of others is in this area.
No matter what you do, be sure to have clean ends on your boards (cut them if needed) and treat them with Anchor seal (or another quality end sealer) ASAP.
Scott
