My wife has dreamed forever of hiking to the river, staying at Phantom Ranch, and hiking out the next day. Tough, but doable. Of course, we would do the popular Bright Angel Trail from the touristy South Rim.
However, I got to thinking what if I threw in a round trip to the top of the much lesser traveled and tougher North Rim Trail? What could go wrong? Just an extra 28 miles on the day and 7,000 of elevation gain.