Spent two nights at the 9 hotel recently and will go back next time I'm in Paris. Rooms are lovely, lobby is cool and it has a very chill vibe. Staff were very friendly and helpful, shout out to Jay who went above/beyond in helping us and let us check in early. Breakfast is good too.
Located a ten minute walk from Gare du Nord, this is an easy option for those coming from London on eurostar.
You can also walk to Galeries Lafayette (15 minutes), the Louvre (25 minutes) and the bars and restaurants within the Opera District.
If you stay here, and want a delicious brasserie, I recommend the General Lafayette (a short walk from the hotel)--- you will be crammed beside other people in this hopping place, but it is not a tourist trap and seems to be where the locals go for an excellent lunch.