FTL
Basically, I do not feel you need FTL for interplanetary travel. Interstellar is another matter.
Warp drive would, however, be interesting as a kind of reactionless drive.
Stopping at 0,99c is essentially the reverse of accelerating - if you can accelerate, you have the way, in principle, to stop.
If you have FTL, you get into problems with speed relative to ether...
What would you do as aerospace engineer with a reactionless drive?