Example 1:
No intelligent person who drinks to excess also eats to excess.
I am stuck on deciding whether this means
a) $\forall x(Ix \implies -(Dx \lor Ex)$
or
b) $\forall x(Ix \land Dx \implies -Ex).$
Example 2:
None of the paintings is valuable except the battle pieces.
I think that what this is saying (using intuition) is that, if you give me a Painting then it is not Valuable unless you give me a Battle piece in which case it is Valuable; thus, in symbols:
c) $\forall x(Px \implies -Vx) \lor \forall x(Bx \implies Vx).$
Alternatively, it could be closer to Example 1; thus, in symbols:
d) $\forall x(Px \implies -(Vx \lor Bx)).$
Or I could very well be out to lunch on all of these translations.
I agree, so: $$\forall x\big(Px\to(Vx\leftrightarrow Bx)\big).\tag1$$
However, there is another interpretation of the word 'except': $$\forall x\big(Px\to(Vx\to Bx)\big).\tag2$$
Everyone except Sue attended the event.
Sue did not attend the event.
I won't take an umbrealla, except when it rains.
When it rains, I may still not take an umbrella.
a) No (intelligent person) who (drinks to excess also eats to excess)
b) No (intelligent person who drinks to excess) also (eats to excess)
Option B is correct because the given sentence doesn't assert anything about moderate drinkers who are intelligent.
Notice that Option B has the categorical structure "No X is Y", whereas forcing Option A to correspond to the natural-language sentence results in the verbal connectives being illogically placed.
For completeness, Mauro's translation: $\lnot \exists x (Ix \land Dx \land Ex);$ note that some (not me) may judge this to be logically equivalent to a translation rather than actually a translation.