Potter's angel is my "holy grail" of nano fish. Fairly hard to find and very hard to keep though. My experience with dwarf angels hasn't been all bad, but I'd definitely put them in the "with caution" category as they have to be watched and will go through phases of bad behavior.
Royal gramma is definitely a cool fish, but you won't see it much even in a semi-agressive tank IMO. Mine always hides in it's little nook and never comes out in the open.
That chalk bass does look neat, don't see them often!
To give you more ideas, here is what I have in my nano: 2 x SA fancy snows, coral beauty angel, ORA neon dottyback, flame hawk, ORA spotted mandarin, royal gramma. My goal was color assortment. The dottyback and hawk are both pretty aggressive, and the angel has it's moments.