We used to always stay on the Left Bank; now we are enjoying the Right Bank more and more. Maybe it IS age--now that I'm in my "quarantaine"--I find myself enjoying the "scene" in the 8th and th 16th every bit as much as I used to enjoy the 6th. I was never a fan of the Marais, though, unlike many here, too crowded, too busy, air too polluted in mid summer (those little streets get a lot of traffic and they really trap the pollution on warm, muggy days).
Paris isn't a huge city, so wherever you stay, if it's fairly central, you should enjoy yourself.