As others have said, what you essentially need to do is start thinking about creating a "super cluster" instead of a "super server".
The Workstation instances are desktop software and aren't really that smart. They won't talk to each other, but if the network settings are correct they can be completely transparent to your vSphere environment.
Configure your network settings so that all virtual ESXi hosts are on the same subnet (and VLAN if necessary).
Once all the network bits are in place, under vCenter (which you can deploy as a virtual appliance as others have suggested or as a regular VM) simply create one single cluster and add all your ESXi hosts to it. Enable DRS and it will autonomously and automatically balance whatever VMs you have across both laptops, pooling all resources together.
Keep in mind though that if your laptops have only one NIC (are there even any laptops with more than 1 NIC out there?) it can be a bottleneck once you start playing with large VMs and features such as vMotion.