Looking at standards for our virtual environment and setting the baseline for vmware tools and hardware level, and os level seem like the first place to start.
digging through the vmware side I found a number of good links that talk about if and when you should upgrade your vmware tools and hardware levels.
Need to know what vmware tool version collates to which ESX version, this is the link for you
Use the product interoperability matrices to find out what version of vmware tools is supported by which version of ESX
Need to understand what the different levels of vmware hardware give you. The information is in the vmware docs site
And finally need to know the compatibility of hardware levels and your ESX version, I found that too 🙂
Based on the information above and that we are currently running ESX 6.5 U2 on our host, looks like my baseline should be vmware tools 9536 with hardware level 8.
Hope this was helpful, if so drop a note in the comments below. Thanks!