Boot Options / Firmware
In VMware, under the VM Options --> Boot Options, there is an option called Firmware. You can choose either "BIOS" or "EFI". I don't have a hard preference, and both will work fine. There are pros and cons to each one. But this setting is one of those things you don't want to change after you've set it one way or the other. I've never seen any difference from an OS or GroupWise functionality standpoint using one or the other.
Pros: It's generally more familiar and I would say simpler to work with. Disk partitioning is very straightforward and simple. With the BIOS setting, you are able to use standard disk tools to manipulate and resize partitions (if you need to expand at some point).
Cons: It is a legacy setting.
Pros: EFI is the standard moving forward and offers some functionality and security not available to the BIOS setting.
Cons: The current toolsets on Linux that support EFI are extremely limited compared to what's available with a standard BIOS. For example, if you ever need to resize a partition, the tools are not available using EFI.
Note that the partitioning you choose will vary depending on which option you choose here.