I can't give you any specific hints, but I can give you encouragement.
A couple of months ago I took most of the family to Europe and we spent about 5 days in Paris. With me was my youngest son and his (long term) partner and his brother (my older son). We all met up with one of their old friends from SFO who happens to live in Paris (not very luxuriously, I'm afraid).
Off they went on buddy's scooter, and that was about the last we saw of them for a long time. Oldest son (who is straight) reported he never had a better time in his life, and looking at his camera pix I have to believe him.
There is apparently no area of Paris where any sort of discrimination was experienced, and not just in the Marais.
All in all, I would have to describe Paris as one of the gay friendlier cities in Europe (with the possible exception of Amsterdam, which is a city we all liked very much).
If I read your post correctly, you will be travelling solo, which is kind of a shame. While you can certainly have a good time alone, it's really better to travel with someone. Of course, who knows who you'll meet ...