I stayed in Paris many, many times before I finally spent time strolling (rolling possibilities are **excellent**) in the Jardin du Luxembourg.
Depending on your point of origin the following bus lines will get you to one of several entrances according to parisinfo.com; 21, 27, 38, 58, 82, 83, 84, 85, 89. That same website only lists one Metro and one RER station, so once again you should think about taking the bus, n’est pas?
This oasis/park can restore your spirits after the frenzy of museum, monuments and mobs. And after you’ve been re-energized you might like to explore the (6th arrondissement) neighborhood!