I have not personally tried it together with placement groups, but we provide AMIs that you can launch with any kind of instance you wish in any configuration. The Marketplace entry on AWS for community may default to a particular type of VM but there again too you can choose a different one.
The marketplace entries tend to be fairly simple and set up to get up and running quickly. If you want to set up Neo4j into a particular network environment on AWS, sometimes you need to do some configuration yourself, and in this case starting with the AMI might be better. Try searching on these forums for neo4j and AWS and you'll find posts with AMI IDs in various regions that you can use immediately.
