Alternatives To Hyperspace

In my teens, I preferred James Blish to either Poul Anderson or Isaac Asimov but have since come to think much more highly of Anderson. Blish always avoided the cliche of "hyperspace" and instead envisaged two other main means of FTL interstellar travel:

The Spindizzy
Attention-Grabbing Ideas
Interstellar Travel

The Haertel Overdrive
Welcome To Mars
Films
Inconsistency?

There is more discussion of these and other aspects of Blish's future histories on James Blish Appreciation.