I-95 vs. US 1. They parallel each other for much of the East Coast. US 1 is full of stoplights and sleepy little towns so on average it's a lot slower, but when I-95 gets backed up badly (ie, anywhere within 100 miles south of DC...), it's good to know that you can pop over to US 1 and get around the backup.
OTOH, if US 1 is *ALSO* fubared due to traffic or construction, *THAT'S* nice to know too, before battling to get off of I-95 just to find yourself in a similarly sucky mess.
Or, for an extreme example, it's usually about 9.5-10.5 hrs to drive up I-95 from Raleigh, NC to our place just north of NYC. (Record is 8hr 17min door to door. whoosh) If, however, traffic is really bad, it can take up to 14 hrs, in which case it's better to pop up through Winchester VA, and take I-81 along the edge of WV, across PA, hit I-78, and then hook back into I287. Almost always 11.5 hrs. You have no *IDEA* how much I wish I could just drag that route on my iPhone when we're around Richmond, and need to make a decision. The traffic map and predictions are great, but dear god I'd love it if I could do the same "Hmmm, try *this* route" sort of strategizing on the iPhone that I can on the desktop.
My other brain is hung like a horse too.
#IRC isn't old school.
Old school is being able to say 'finger me' with a straight face.