Archiving content in SharePoint libraries
Well, one is redundant, Dispose() on the site object is done for you automatically in the context of using. To be idiomatic in C#, you should do the following:

using (var site = new SPSite(connectionString))
using (SPWeb web = site.OpenWeb()) // open the site
{
        try
        {
            Console.WriteLine("[{0}] Opened site: {1}", DateTime.Now.ToShortTimeString(), web);
            Console.WriteLine("[{0}] Web Relative URL is: {1}", DateTime.Now.ToShortTimeString(), web.ServerRelativeUrl);

            // Get your source and destination libraries
            var source = web.GetList(web.ServerRelativeUrl + @"/Approval%20History%20%20Sales1");
            var destination = web.GetList(web.ServerRelativeUrl + @"/Approval%20History%20%20Sales");

            Console.WriteLine("[{0}] Source set to: {1}", DateTime.Now.ToShortTimeString(), source);
            Console.WriteLine("[{0}] Destination set to: {1}", DateTime.Now.ToShortTimeString(), destination);

            // Get the collection of items to move, use source.GetItems(SPQuery) if you want a subset
            SPListItemCollection items = source.Items;

            // Get the root folder of the destination we'll use this to add the files
            SPFolder folder = web.GetFolder(destination.RootFolder.Url);

            Console.WriteLine("[{0}] Moving {1} files from {2} to {3} - please wait...", DateTime.Now.ToShortTimeString(),
                              items.Count, source, destination);

            // Now to move the files and the metadata
            foreach (SPListItem item in items)
            {
                //Get the file associated with the item
                SPFile file = item.File;

                // Create a new file in the destination library with the same properties
                SPFile newFile = folder.Files.Add(folder.Url + "/" + file.Name, file.OpenBinary(), file.Properties, true);

                // Optionally copy across the created/modified metadata                        
                SPListItem newItem = newFile.Item;
                newItem["Editor"] = item["Editor"];
                newItem["Modified"] = item["Modified"];
                newItem["Modified By"] = item["Modified By"];
                newItem["Author"] = item["Author"];
                newItem["Created"] = item["Created"];
                newItem["Created By"] = item["Created By"];

                // UpdateOverwriteVersion() will preserve the metadata added above. 
                newItem.UpdateOverwriteVersion();

                // Delete the original version of the file
                // todo: make local backup before deleting?
                file.Delete();
                fileCount++;
            }

            Console.WriteLine("[{0}] Completed moving {1} files to {2}", DateTime.Now.ToShortTimeString(), fileCount,
                              destination);
        }
        catch (System.IO.FileNotFoundException)
        {
            Console.WriteLine("[{0}] Unable to set a location. Please check that paths for source and destination libraries are correct and relative to the site collection.", DateTime.Now.ToShortTimeString());
        }
}