Splurges we found well worth it on our 2015 trip were a food tour (Paris by Mouth) of St. Germain and guided walking tours (through Paris Muse) of the Marais and the Louvre. We took the train to Chartres for a day trip to the cathedral and to Bayeux for a two-night trip which included the tapestry and the DDay beaches. We booked a Dday tour with Dale Booth, who was excellent - this was DH’s favorite experience of the trip.
We economized on meals, which wasn’t as hard as I thought as even the inexpensive restaurants we ate at were fine to very good. We had a couple nice lunches, but dinner was pizza/falafel/Thai/crepes etc. And yes, we adopted the “goûter” practice most afternoons and enjoyed picking up a treat at a patisserie or boulangerie to enjoy in our room with a cup of tea or glass of wine while we rested our tired feet. We had read that the city of Paris was cracking down on short-term rentals and were nervous about finding ourselves on the street, so we stayed at a hotel, La Clef d’Or (fabulous breakfast included when we joined the affinity program, not sure if that is still the case), and our room had a small frig, microwave, & Nespresso machine.