Pittsburgh to the Grand Canyon is a bit more than 2,000 miles, one-way. Like others, I'd be a bit hesitant to cram that much driving in a 10-14 day trip. 500 miles per day is a lot for one driver in a RV, more so several days in a row. With two drivers, maybe you can go further, but you're still arriving late, setting up late, and moving on early the next day. Could be worth it for some, and careful planning may make the stops more enjoyable, but if I only had 10-14 days, I'd think about closer destinations, even multiple destinations, where driving wouldn't be such a large chunk of the trip. YMMV.