Well, let's see... Our project to upgrade just 4 SQL servers is going on 2 years, now. The biggest thing that seems to be getting in our way is getting approval from the business unit that their applications support SQL Server 2008 R2... Yes, that's right, we're not even talking about 2012. Once all applications on a particular database server have signed-off the nightmare of getting the VM provisioned begins. Forms are completed, emailed, printed, signed and filed off somewhere. We have meeting-after-meeting about the CURRENT and TO BE environments, SQL licensing, and Disaster Recovery.
For the most recent iteration of this project (new SQL server 2 of 4) it took 7 months to go through all of the red tape and get the VM Provisioning specs finalized and approved. Total time from spec completion to VM build... 2 more months. Once it was turned over to the DBAs, total time to get SQL Server installed (Slipstream SP2), configured, and all databases migrated and integrated within existing maintenance plans... 16 hours. **headdesk**