I would recommend using a full CAS. Whilst calculators are good as quick tools, they are very slow (to input and compute), cannot output to file, and generally not helpful beyond that. Since everyone is always around a computer (laptop), a full CAS that computes everything and generates all the graphics would be the most ideal.
For Monash kids, you get Mathematica for free while you are enrolled.
http://www.its.monash.edu/staff/software/catalogue/If you are not at Monash, there are alternative means. (cough)
It is the industry standard CAS, extremely powerful. Learning to use the basics isn't hard, mastering it takes a bit more, but when you get used to it, you can do everything at extreme efficiency. (I use it for all my assignments and research)
For people using the Android architecture on their phone, there is this app called 'HandyCalc' on the market. Its capabilities will surprise you, it's like having a graphics calculator on your phone (graphing, solving, etc).
The combination of these two pieces of software meant I have not taken a calculator to uni for 2 years.