Route53 Routing Policies - Best Policy for US-based Ecommerce?
To answer your question, ill first try to give simple explanations for each policy to help with the confusion (https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy.html).


Simple: a basic routing policy that randomly sends a user to one of
your addresses.
Failover: You have a primary (active) route and a secondary (passive)
route. When the primary fails, it routes to the passive. If passive
fails, you have an issue.
Multivalue: Multiple routes that each have health checks. It will randomly select an address (Simple routing policy) from the healthy routes. A more
complex failover policy.
Geolocation: Route users dependent on where they are located. If a
user is in England and gets better latency in Germany, they will
still be routed to England.
GeoProximity: A more fine grained Geolocation. You would be able to    route people located on the border of France and Germany (based
on longitude) to a    specific route. "Traffic Flow Only" is to
specify that you must use the Route 53 traffic flow to configure this
policy. It is the most complicated of the route 53 policies
Weighted: This policy allows percentage based balancing. Routing 30%
of people to route-1, 20% to route-2 and 50% to route-3.
Latency: Route to the address that gives the user the best latency.


Now for your architecture, your current implementation would handle instance failures with the ELBs and the latency based routing (with health checks) would handle the routing failures. If you don't require routing your users to the lowest latency address, use the multivalue policy instead.