I like overland. As long as it elevated a decent height and well lighted the chance of mob interference is nearly as equal as that as underground.
Either way I don't think there should be more than a few lines. I don't think we need it under every road to every plot.
Perhaps only 2 straight lines. Like one north/south and one east/west line would cover about everything needed.
As far as electric goes to each plot there could still be a much smaller underground line for bringing electricity from the spawn reactor. Or can run a line with battboxes with an overland system to connect to a series of electric hubs that could then run underground from those points to plots.
Playing: Minecraft, Landmark, EvE
Retired from many, incl: WoW: Aesha, Kael'thas; FFXI: Ehlynia, Pandy; Tera: Ehlynia, PvE.