Adam Hibberd
Here's a mission to asteroid Psyche for you.
Initial theories favoured Psyche as a core of a failed protoplanet, containing vast reserves of metals. More recent research, however favour alternative origin theories. Whatever is the case, we are about to discover its true nature and this would be a huge step forwards for humanity, especially if such bodies can eventually be mined.
The real mission is planned to launch early October and will use SEP (Solar Electric Propulsion) which is a low thrust but high Specific Impulse engine, which measures out its thrust slowly but surely and also very fuel-efficiently.
We can approximate a SEP trajectory with OITS by exploiting many consecutive Intermediate Points (IPs) or alternatively known as Deep Space Manoeuvres. However when I attempted to do this, I found replacing some of these DSMs with planets (either Earth or Mars) resulted in more fuel-efficient trajectories albeit using high thrust rather than the low thrust SEP.
Note that an issue with this trajectory would be the high approach velocity the spacecraft would have with respect to the target which would ultimately have to be removed to rendezvous with the destination. That would require fuel mass.