hello!
I suppose that really depends on what you enjoy more, nature or culture. there are not many big towns to choose from.
o barco de valdeorras is the first you come across but there is not much to see, just pretty houses and a river promenade.
a rua is the second. you can explore the old village of fontei where there is the private albergue, the old centre a rua vella and make a short walk to roman ponte cigarossa (about 2km one-way). I'm sure asunción from the albergue can make other suggestions.
from quiroga you can go see the former hospital of knigts of st john (about 2km one-way) but apart from that there is not much else.
monforte de lemos is the biggest town on the route and there is probably enough to occupy one day. the old town, the castle/monastery, convento de clarisas with museum, colexio NS antigua with museum, pazo muinos de antero (19C mill with a curious security system of peep holes), cruceiros, ermita s Lazaro with an inscription that mentiones a refugio, a stroll along the river, some good restaurants (o xugo on the square at colexio NS antigua, for example).
lalin is also bigger and has, for me at least, a very nice and relaxing atmosphere, two museums, one of an astronomer and one of puppets, and the old centre above, lalin arriba, where the route arrives (don't miss the church with shells all over!).
las medulas is certainly worth one whole afternoon (at least 2h30-3h), but apart from that there is nothing else there.
but for a day with legs in the air, I would say barxa de lor = a ponte with the fine medieval bridge (pension is supposed to be about 300m away, and another further along the main road), or santo estevo with the romanesque church with a beautiful portal (this one is about 3km off route and has an english-speaking BB where they tell you how to get there from diomondi).
hope that helps a little.
