Prepared queries that include results from multiple DCs

We have a use case that we're trying to accommodate with prepared queries, but can't quite get to work. We're trying to setup puppet SRV records, https://docs.puppet.com/guides/scaling_multiple_masters.html#option-4-dns-srv-records.

We can get a prepared query setup that almost does what we're looking for, but not quite. The catch is that we have multiple "well connected" datacenters in a region and want to return all of the puppetservers across those sites, not just the ones in the current DC. This would be analogous AZs within an AWS region.

The Failover functionality is almost what we want, but not quite. We want it to return things from a list of datacenters always, not just as a failover.

It seems slightly related to https://github.com/hashicorp/consul/issues/671, and https://github.com/hashicorp/consul/issues/252 would likely be useful as well, but isn't 100% required.

Anyway, I'm happy to open an issue in the repo to discuss, but I wanted to reach out and check to make sure that I'm not overlooking something or failing to find a previous issue about this.

Moving to an issue from the [mailing list](https://groups.google.com/d/msg/consul-tool/UZqGRpqeBtQ/uHW5b8MMBgAJ).

/cc @slackpad