My wife and I had a great stay at Paolo's place. The price is great for this sort of location - it's already in the centre (within city walls) and probably 10 minutes' walk to the central square. It's also very well positioned for the long, long walk to the San Luca sanctuary which is a must for any visit to Bologna. Walking to the railway station (we did this once or twice) takes just about 20-25 minutes. It's probably a flat for 2 but I think it can sleep 4 if you really need it. Amny good restaurants and nice breakfast places around.
Paolo is a great host, he gave us useful tips on what to do in the city and was always there when we needed him.