It depends a lot on what type of car you are looking for. I have the SE package on my 2.0TDI and I am very happy with it. Others on the forum much prefer the Sport package. The ride is harder with the Sport package and you get Sports Seats, which personally I am not too keen on. Before I bought my A3 I test drove both a 2.0 pertrol and 2.0 diesel and the diesel was by far the better and more powerful package. The SE eers on the side of comfort and luxury whereas the Sport is a more sporty package with harder suspension and larger wheels and tyres. I drove both the SE and the Sport and preferred the SE. As I say it all depends on what you want from the car.
The 1.6 will not be a particullary powerful car, if anything I would say slightly under powered so there would seem little point in going for the Sport package unless you prefer the look of the larger wheels and want the Sports seats. Do you have a particular reason for going for the 1.6? Others in the range would give you a better power to weight ratio. Also are you aware that the tiptronic on the 1.6 petrol will not be a DSG but a conventional automatic.