[busterbrown]

The wife, kids and I are going south towards Columbia, SC to see the fast approaching solar eclipse of 2017. Our trip begins from the Detroit area. Our final destination is the Fort at Disney. Google has routed us down I-77 into Columbia. As this is the fastest route, I'm wondering how the grades are verses the more popular southbound route of Interstate 75. We have a 35 foot trailer in tow.

Alternatively, we could always take I-75 south towards Knoxville, TN then I-40 east connecting to I-26 east into Columbia.

Looking for a relaxing drive, not necessarily grade after grade after grade. I've done I-75 from Detroit to Florida at least 30 times in my life. I've never travelled the other two routes. Any comments on I-77 road conditions, grades, fueling stations, and rest stops are appreciated.