Hi Gerri,
I've been to Lourdes via the TGV from Paris. The Pyrenees are beautiful, and Lourdes is quite the picturesque setting. The town is essentially downhill from the train station. There's a stat (guess it's accurate) that Lourdes has the most hotel rooms in France outside of Paris, and I can believe it.
Things I did:
Grotto
Upper church
Underground church
And I highly recommend the fortress and the museum of Pyrenees history (Chateau Fort). There's a fantastic view from the top of the fortress that lets you take in a 360-degree view.
https://en.lourdes-infotourisme.com/web/EN/381-chateau-fort-de-lourdes.php
I'm Catholic, and yep, Lourdes has a lot of ticky-tacky souvenir shops, and it can be a bit overwhelming in the town, but once you get to the shrine/religious area it is peaceful and park-like. I was on a group trip and we were staying in one of the ski towns higher in the mountains, so I did not spend the night in Lourdes. We were just there for a full day of sightseeing and lunch.
Have a great trip!