Those are some very interesting customs! I'll reply about each one.
Clone Sniper - I like the looks of this guy... at first the helmet piece looked a little odd, but it's grown on me. Heck, there's so many different looks to the clones in ROTS, that this one would fit in just fine. Plus it's not just another repaint, it's an all new look. Great job!
Boba Fett - Nice, clean and crisp custom. Does the helmet fit?
Palpatine - I agree, that matches the movie version better. Maybe add just a hint of paint to his face to make him look more weary (not evil Palps yet, but a little more like an old man).
Mace - Looks good, looking forward to the completed version. The changes you have planned sound great.
Clones - Both look cool, the one on the left I think needs some gray pants, and make all of his armor gray too perhaps. I don't know... just throwing an idea your way.
The second one already looks cool. I think painting some dark/blood red stripes on him in the 501st paint pattern might look really good.