This may help if you want company. It's a newsletter I get.
http://www.metropoleparis.com/aclub.html
A group of mostly Americans meet at this café on Thursdats.

Cool. Have you tried it?

No, I haven't as I usually don't stay in Pars and head out to the provinces but have been getting this newsletter for a few years and thought, I should share it with the younger, single first time visiters to Paris.

My husband and I always go to the Corona [cafe where the Metropole cafe meets] when we're in Paris. It meets from 3 to 5 pm on Thursdays. You get to talk to other visitors and some interesting people currently living there. It's casually "run" by Ric Erickson and is an enjoyable break in the tourist routine.

I go as well and look forward to the newsletters. Particularly Ric's addition of the calendar of events...

While visitors in just for a period of time show up, there are quite a few ex-pats who show up as well to meet and make new friends...