Hi! We've eaten at both & preferred Bistro de Paris, b/c the restaurant itself had a more romantic atmosphere. I say "the restaurant itself," b/c it's one of those in-park restaurants, so it tends to be a lot noisier than, say, Citricos at the GF.
On our two trips to Bistro, we heard a LOT of crying children, saw a woman wearing no shirt or pants, just a bikini & sarong, saw a boy (5th-6th grade age) who kept mooning people & picking his crack, and watched kids dashing around the waiter, as he set the Crepes Suzette on fire (I noticed this, b/c I was so worried one of them would get hurt, but their parents laughed & thought it was funny that they were so excited by the fire. The crepes were being served to another table, not this family's table, and I thought if I were one of the people being served, I would be worried about a child bursting into flames in front of me!).
In our experiences, the resort restaurants tend to be a lot quieter in general, and, possibly b/c people go to their rooms & put on clothes, everyone seems to come fully clothed to dinner. So I don't think I would go there for the romance, unless you're impervious to scenes like those described above. Then again, I'm a teacher, so we always go in the summer, when there tend to be a lot more kids. And I may be more on the lookout for kids doing something dangerous, just b/c I'm used to being on teacher alert!
Chefs de France seemed even noisier than Bistro, but we weren't bothered by it; it just struck us as a restaurant with a high noise level.
You asked about Illuminations; we could see the fireworks, with a somewhat obstructed view, from our table at Bistro. The sounds weren't piped in, though.
Cheers!
Heather W