It takes some fuzzy math to quantify upgrades into SPG value, because you would have gotten the upgrade even if you had paid cash as well.
Therefore I'll list the cpp for SPG compared to the base rate and the upgraded rate.
Stuff I've used SPG for:
20K SPG for 50K LAN for a ticket to Brazil with a regular price of $1,000.
$1,000/20,000 SPG=5.0 cpp.
-Westin LAX, cat.2, Regular room price was $230 with tax, was upgraded into a terrace suite which was going for $450 with tax.
Base room: $230/4,000 SPG=5.75 cpp
Upgraded room: $450/4,000 SPG=11.25 cpp
-Le Meridian Haifa, cat. 1 at time of stay, regular room price was $200 with tax, paid 3,000 SPG.
$200/3,000 SPG=6.67 cpp
-Le Meridian Dead Sea, cat. 1 at time of stay, regular room price was $300 with tax, paid 3,000 SPG.
$300/3,000 SPG=10.0 cpp
-Sheraton J'lem, cat. 3 at time of stay, regular room price was $400 with tax, paid 2,800 SPG+$45 with C&P.
$400-$45=$355/2,800 SPG=12.68 cpp
-Herods Vitalis Spa Eilat, cat.3 at time of stay, regular room price was $500 with tax, was upgraded into the presidential suite which was going for $1,500 with tax. Paid 2,800 SPG+$45 with C&P.
Base room: $500-$45=$455/2,800 SPG=16.25 cpp
Upgraded room: $1,500-$45=$1,455/2,800 SPG=51.96 cpp