I suppose the first question to answer is what will happen if the circuit fails? If it will not cause any safety related issues if it fails, then there's no real harm in using standard COTS parts. Unless you plan to buy a large quantity of parts now to support possible future production of this device, you won't get any sort of price break to buy the automotive grade parts initially either.
I'm not sure that the 12V automotive grade regulator will buy you much over using a standard low drop out regulator and adding some good filtering if you plan to use COTS downstream parts either. The primary benefit from the industrial/automotive grade parts is they are screened to survive the wider temperature range. Also, if you have a 12V input, you don't really need to go with LDO regulators for the 5V regulator. And you don't show any of the filtering or the biasing for the LM1117 regulators. Hopefully those were just left off for simplicity and not because you don't plan to incorporate them.
Is what you're powering off of 12V extremely voltage sensitive, or is it rated to work over a rather wide voltage range? Maybe you don't even really need a 12V regulator and can instead focus on filtering the input to the downstream voltage regulators.
The more I think about this, the more I wonder if you've looked around for any multiple output buck converters that will provide you with all three desired voltages from a nicely filtered, DC-to-DC converter....
-Rod