For as far as I'm aware, you don't need more than one IP for any of your services, unless you plan to run multiple services on the same port. The only reason I can imagine for why you'd want a /30 subnet is to either:
- Have multiple services running on the same port - They would obviously require a separate IP then
- Separating public services (VPN, website, etc.) and regular outgoing connections. So (for example) the stuff you can use from outside your network uses the IP 188.8.131.52 while your home computer has the public IP 184.108.40.206 when you browse the internet
- Server with dedicated IP
- Showing off to your friends ("Hey guys, guess who has two IP addresses?")
I would personally setup something similar to use-case 2 above, where services are all hosted on one IP address, and your "regular" traffic stays on the other IP. This might also help with firewalling, but I'm not sure about that.
3: Server with dedicated IP
I imagine you have some server sitting at home that runs all your different services, if this is the only machine that offers stuff to the public internet (web hosting, vpn, etc.), I would give that machine the extra IP for itself, so that you don't need to do a lot of firewall magic and let the server handle its port assignments and stuff by itself.
This also applies to the VMs inside a VLAN. You could assign the VM host server a dedicated IP, and then let it figure out the NAT forwarding etc. by itself. That way you could also easily cut off all public services without breaking your own internet connection by simply disabling the public IP.
EDIT: I believe this answer on the unix stack exchange gives a lot of valid reasons to have an extra IP - Except for the hosting of multiple SSL sites, since I don't believe that's a big issue anymore, with most browsers now supporting SNI