Handle the PrepareViewStyleInfo event, and then conditionally set the e.Style.BackColor in what ever manner you like. For example, you can do every 3 rows instead of every other row :)
private void gridControl1_PrepareViewStyleInfo(object sender, GridPrepareViewStyleInfoEventArgs e)
{
if(e.ColIndex > 0 && e.RowIndex > 0)
{
if(e.RowIndex % 3 == 0) //use 2 for every other row
e.Style.BackColor = Color.LightBlue;
else
e.Style.BackColor = Color.White;
}
}