Design of RDS infrastructure

hi there,

I've been asked to look at a design of a new RDS infrastructure for a new office.

It will have 300-400 users and should be fault tolerant where possible. They will have new servers and SAN and we will be using win 2012r2.

In terms of the connection broker I understand this requires a SQL database. Can anyone suggest how this should be architected. i.e. should there be a failover cluster (always on), should it have NLB? 

I'd be interested to hear thoughts on this.

Thanks

Alg