Sestriere is considered the main ski range of the Via Lattea (milky way) mountains. Its most famous visitor being Alberto Tomba who, in 1987 won his first world cup slalom race there. I think that said slalom run (located at the start of the pistes) is the best on the mountain. All pistes are southern facing so when the suns out, they can get a little slushy but the resort has fantastic snow making facilities. Prices on the mountain are generally fair and all mountain restaurants serve traditional pasta and pizzas. Off piste runs are fantastic and you don't have to trek far away to find them. There is good deal of beginners runs (the ski instructors are excellent) but if you are an advanced skier you may get a little bored as none of the runs are too steep.
Nightlife is not particularly good but if you are traveling with a large group you will always find plenty of entertainment in one of the many bars. I find the Igloo bar best for apres ski or head to Pinkies Pizzeria (the pizza there is fantastic!)