The Mon Calamari cruiser could probably built using the more bulbous basic hulls (like Yor) and simply stacking objects until you can start fine tuning with smaller objects. Remember, most of the cooler ships you've seen here use several clever ways of arranging the standard parts to simulate a single hull. Don't be afraid to alter hardpoints, either.
The Close Encounters one could probably faked using the wheels and large versions of the dishes that you'll see in the generic styles. Find a pole-type piece and use that as your basic stem. Then scale the discs up and down to get that tapered feel. Again, the best way to get the correct orientation is to alter the hardpoints by rotating them so that the basic hull is in a vertical orientation rather than horizontal.
Hope these suggestions help.