Connect to SQL Server using OLEDB or ODBC?
For most applications hitting SQL Server 2008 R2, you would be fine going either way, I think.

OLEDB support is being removed after SQL Server 2012 but until it is, you'd likely be fine either way based on your standards and your needs. That said, I'd look to future supportability and consider going ODBC with the Native Client.

I would say a more important decisions would be to consider using the Native Client for your .net apps if you aren't already.