Favorite/Easiest LTW?

[chemeia]

My favorite is Presenting the Perfect Private Aquarium.  I enjoyed setting up my showroom, naming the fish, etc.  Swimming in Cash is the easiest, even without cheats.

[Monolito]

I'd go with the one requiring max athletics and martial arts. You will get them anyway so...

[Leto85]

I'd go with the one requiring max athletics and martial arts. You will get them anyway so...

Combo-skilling is indeed a practical thing to do. Especially if they provide your done with something extra, like a gem collector, as your example can be. A LTW that go hand in hand with that makes it even better.

[Monolito]

I think you train athletics at the same time as martial arts while using the training dummy. Correct me if I'm wrong.

[Schipperke]

I think you train athletics at the same time as martial arts while using the training dummy. Correct me if I'm wrong.

You're quite right.  Using the training dummy, sparring or breaking boards with the board breaker - all raise both the Martial Arts and Athletic skills.