I-81 and I-99 in PA

I like the "Susquehanna Trail" road, US 15 from H'burg north to the PA/NY line. There's a bit of congestion around Williamsport, and also down around Sunbury, but other than that, it's a pleasant road. I've done it three times in the last two years or so. From W'port north to the PA/NY line, it's interstate-level in everything but name and signage. From W'port south, except for the area noted, it's almost all four-lane. South of I-80, it's almost perfectly flat. I did a dash-cam of the section from I-80 south to Harrisburg last May, it may be of interest.

https://www.youtube.com/watch?v=9fmUA0Wb42w