Don't know if I can answer this well however most people who go to Lourdes do so on pilgrimage. The main location is the Grotto so most activity revolves around there. There is also St Bridgets bed, a house with a bed where St Bridget slept. If you go there you'll realise there is more to Lourdes than you realised as you'll see the river that flows though it and quays and more of the town as you make your way there. If you want a quick tour of the religious sites you could do them in a day, beyond that I was never brought to see more of the town or the surrounds.
Regarding getting there, it involves quite a long, sometimes scary drive through some hairpin bends through the Pyrenees so it takes a bit of effort to get there. You'll get to see alot of the Pyrenees on the way if you're not on the floor of the bus with fright like I was as a kid. about 8 years ago