I can (manually) open them using File->Open... and selecting the .vagrant\machines\puppet\vmware_workstation\some-unique-id...vmx file. But that's a bit annoying. Using VirtualBox, vagrant VMs are automatically added and removed from the Virtualbox GUI.
VMware Workstation helps organizations deploy many applications and operating system workloads on a single server. Thus, it helps in better resource management. The workstation is an efficient and advisable solution for local desktop virtualization as it lets you securely run an additional operating system as a VM on a single computer.