I would highly recommend the Hotel Montebianco, located near Piazzale Lotto. Not right in the city centre but you're less than 10 mins away from town on the tube. The Metro station is right in front of the hotel.
It looked like it had been recently refurbished, so everything was nice. However, we had a room facing the main road (Via Monte Rosa) meaning that there was a bit of noise, not from traffic, but from people probably exiting a nearby Brazilian restaurant quite late at night. So maybe you'd want to play it safe and have a room facing internally.
We booked on Venere.com for €80 per night for a double room. I had called the hotel to check on prices and they quoted €140 and suggested I book through the internet to get the better offer.
I think the most pleasant surprise was the breakfast buffet! I've become used to mediocre cappuccino and a croissant or crackers in 3-star Italian hotels... but here they had a relatively large buffet with a orange-juicer. It was great!
