Starbucks @ Avenue de la Motte-Picquet

While I imagine Starbucks in the antithesis of the type of environment LTF is going for, I'd say that SB La Motte Picquet is one of the more convenient places for remote workers to camp-out in in Paris. For the price of a coffee you can spend hours here with no one paying attention to you. Accordingly, I always see many others working off their laptops in this particular location so people are generally mindful of each other and their belongings. As it's a Starbucks near the Eiffel Tower, there's a lot of foot traffic coming through and it can be noisy, which may not be ideal for calls; but this means high turnover on seats so you'll never be waiting long for space as there are many tables and chairs both inside and outside.