Beanstalk doesn't like having more than one virtual host per application/server/load balancer. You can do it but its a lot of custom code to make it work. Beanstalk does do deploys very well though with automatic deploys to a subset of instances, checking they are working, then deploying to a new set of instances. Big fan but it is really designed for one domain per instance set.

Beanstalk handles the load balancing for you and throws a DNS entry in front of it all, as far as I can tell. Works well so far. It's smart and (seems to do) blue/green style deploys for my single app instance atm I believe.

(I'm only running on a single box so far, mostly using it because it made deploying to production and all the annoyances that come with that a breeze).