Looking for a great spot for drinks/dinner between Montparnasse and the 7th
The bar of Ciel de Paris on top of the Tour Montparnasse (highest building in Paris)... mostly a champagne bar but also cocktails...maybe 10-walk to Joséphine.
Rosebud on the rue Delambre off the boulevard Montparnasse in the 14th... legendary/ old school... 10-15 minute walk... doesn't open until 7pm so won't do if your friends have an early dinner rezzie.
Piano Bar at the Closerie des Lilas on the boulevard Montparnasse @ avenue de l'Observatoire in the 6th.... maybe a bit far (20-min walk) but station de taxis just around the corner on the av Observatoire... would be my choice because of the history and sparkle.
Of course it depends where in the 7th and Montparnasse but a few ideas include (I tend to go to new places so these are relatively) Bistro Belhara, Le 122, Les Climats, Es, Grand Bistro de Breteuil (despite being one of several might work best for drinking and eating on impulse), Garance & Philippe Excoffier.