Each company is unique in terms of what they want to move to the cloud and when they want to move to the cloud. For most companies, the first area to use cloud services begins with inbound threat protection: eliminating spam, viruses and other threats. At the same time, companies can ensure data loss prevention with an appliance. When ready, all these services can be migrated into the cloud. Other companies may choose a two-layered approach: SAAS for eliminating spam and providing capacity on demand, coupled with appliances for flexible, global administration.
The question to ask here is, does the cloud provider have the level of customization that your enterprise needs? Large enterprises have completely different needs than small and midsize businesses. Not all cloud vendors have the capability to offer the two-layered approach, scale to the needs of a growing organization or offer a phased approach to moving services to the cloud.
Looking at your own organization, can you identify what services should be moved to the cloud first? If not, will the vendor help you determine what kind of customization is necessary for your enterprise? Will the vendor help you consolidate a range of services in the cloud?
It's worth looking at these different scenarios to adopt the right long-term cloud solution. Imagine what a nightmare it would be to move from cloud to cloud as your company grows.