Rar, the "pathways" — whatever they are — while very numerous, do not connect the three towns. Each has its own, with the most to be found mostly radiating from Pitigliano (or more accurately, from a small area in the valley of the Lente below the town), the next most around Sovana, the fewest near Sorano.
In terms of actual ancient remains (not quite certainly Etruscan, but probably), the most stuff centers on Sovana — where there is, to my knowledge at any rate and as of the last time I was there in 2000, no hotel, although a good restaurant. Apart from the "vie cave", these remains are almost all tombs, and many of them are conveniently located in a sort of necropolis area, signposted and crawling with fellow tourists. There are a number of other isolated tombs around Sovana, fewer visitors by far, but some quite worthwhile.
Sorano and Pitigliano are in sort of deep pits in the high plateau: it is the plateau that connects the three towns, and it is flat and relatively dull, although one very curious ancient
thing is to be seen on the road between Sorano and Sovana, the so‑called "Mano d'Orlando", a large hand-shaped rock. Sovana is on the top of the plateau, but the main necropolis is on a declivity away from it.
Pitigliano is actually on a hill that rises near to the level of the plateau, but it's an outcrop from the pit with the three rivers, and it's down in or towards that pit where you'll find the vie cave, the so‑called Tempietto, etc. Also, to get out of Pitigliano you walk steeply down, then back up.
Photos and diary entries of mine on the area are scattered over two (or three?) trips; the easiest link is thus
this one.