In the US, of the five core engineering disciplines (Chemical, Civil, Computer, Electrical, and Mechanical) the rank in pay goes something like this:
Highest Paid:
Chemical
Mid Range:
Electrical and Computer
Low Range:
Civil and Mechanical
Masters degrees do not seem to add much...
I'd suggest sticking with the TI if that's all you have ever used.
Learning how to input calculations using RPN (Reverse Polish Notation) is a royal pain if everything you have been taught up to this point has been using traditional algebra input.
The TI-89 is my favorite as well.