A few issues/questions with that: 1) Local traffic: if this were an enterprise app hosted on premise, with cloud backup, but with some remote users, you'd need to be careful in network configuration. With firewalls, people also access local apps on different IPs than from outside. This may not apply, and certainly can be resolved, but would require some visibility for the provider into your network configuration. 2) Failover: To do this really easily as a service, you'd ideally run 100% of traffic through a third party service. Some of it would get directed into EC2/cloud provider of choice, and some into your colo datacenter. If you're willing to use something like CloudFlare for DDoS/etc. prevention now, this would be the same compromise. 3) Database: Dealing with all the replication issues. If it's static content, this is trivial. Otherwise, you have a consistency problem for databases, etc., and most cloud providers (especially Amazon) want to lock you into weird onsite proprietary data solutions which don't

The best system today is probably to host at a facility with great transport to Amazon Direct Connect nodes (e.g. SV1/SV5 in Silicon Valley -- I'm setting this up now), so you've got fast cheap ways to keep your databases replicated between AWS and the free world/your own colo.

For inbound traffic, for $20/mo, I'd just do Cloudflare; for higher end, you'd have a lot of choices to make. (I haven't tried the higher end cloudflare offerings yet; they do seem to address most of the shortcomings, and are still pretty cheap).