i figured we could build both road and rails at once, lighting wasn't a consideration really assuming most people will only use the roads for horse travel, and mobs wouldn't be a big issue if the roads were made of slabs since they wouldn't spawn on them.
As far as netherrack taking 4 times as long to mine as cobble that isn't the case, netherrack is extremely soft and takes few swings with a pick to break, once diamond picks are aquired it will be like cutting threw butter.
I noticed a number of people are opposed to the netherbrick as they feel that it clashes with their builds, i tend to disagree with that myself. Initially even colored clay was an option, and none of the vets or seasoned seemed to like the idea, plus it would have been one of the more expensive options as far as resource gathering goes. Although carpet is a nice way of hiding lighting i think it wouldn't look right as outdoor roads, perhaps someday Mojang will consider adding "plates" that are thin like the carpet in the future.
For the time being i suggest building the basic roads at first then worry about lighting later.
Btw here is the current winning design as of Monday