Snow troopers would be very cool... they even looked good in that echo base level of SOTE.
In fact.. a snow based level would be cool.. the one in DF was... especially with tauntauns, snow troopers, falling ice, snow beasts etc.. Imagine throwing your saber to drop stalagmites on stormies... Or just colapse the whole coridoor on them.
Some stormies with those big heave blaster weapons that had to be set up on tripods would be cool as well. (I think they had those in SOTE as well). It would be really cool if they ran in and started setting them up, so you had to take them out before they were in place.
Some swamp/rubbish levels with those trash-compactor snake monsters that were in DF1 would be cool too... they would look much better in proper 3d.
Some big dragons/creatures are essential.
Assasin droids would be nice...if they made them really evil. NOgrhi would be very cool... As would undercover stormie infiltration squads dressed as regular citizens.
Sand people on banthas.
Dark troopers, crimson guard. all cool.