Intra-continental I don't think anything beats high-speed rail. Inter-continental I don't think high speed rail is viable, unless you have a transatlantic locomotive in your pocket that you aren't telling anyone about.
Most of the population of the world lives on 2 contiguous land masses. Flights to bridge the masses is fine but would represent a small fraction of the transport needed.
Rail doesn't have to solve all problems. It's a good solution to most problems.
But back to the blimp proposals, I can't see how a blimp would be a better option vs a boat. (Traditional flight is probably better than either).
Imagine a hexagonal grid of these between continents, with aqua-farms, data-centers, resorts, casinos, floating cities/solar/wind sprinkled in between. Err... Aqua-Loop?
Maybe 'grow' them 'in-situ' like corals, funghi, sponges, seaweed, algae, bamboo, whatever, by means of genetic manipulation.
edit: Not to forget, conduits for HVDC, ZBLAN, and all sorts of pipelinable stuff for the global super smart grid.
FUCK YEAH!
edding: Icebergs, yes, yes, Gridguards no less!