Well if it's taking 13 hours to backup just 16GB of data to tape I'd say your first order of business is to resolve the problem with your backup speed, as that's way slower than you should be seeing. Things which could cause slow backups are faulty tapes, a faulty drive, wrong drivers or firmware. Try updating the drivers and firmware on your drive and see if that makes a difference. Also if you're currently using software compression on the backup jobs consider turning it off and seeing what difference it makes, since you've got plenty of space on the tapes to backup all your data without needing to compress it.
After that I'd probably go with two backup jobs, one for Monday to Friday which will go onto tape each night, and then Saturday and Sunday using backup to disk. Obviously the weekend jobs won't be much use in a disaster, but it's better than nothing and at least covers you if someone deletes something over the weekend. Just make sure to exclude your B2D folder from your backup jobs!
You could look at doing incrementals instead of full backups each day, but 1) it'll make restoring a lot harder, and 2) once you've got the backup speed issue resolved the time taken to do a full backup should stop being an issue.
As for best practices info, I don't think I've ever actually seen any, certainly any which is any use. Generally most documents just tell you to make sure you have backups, make sure you can restore from your backups, and make sure you regularly test your backups... except that manage to fill several pages saying the same thing! :) If you do find something though let us know, it'd be interesting to see.