I am still struggling to understand the CLEAR differences between them.
Scuse my ignorance
If you will note closely, the "plain" Pickit 2 comes with a 16F690 20 pin chip which is removable (very handy). The Pickit Express has another chip which is permanent to the board.
So what?, you may ask. Well, you mentioned using several other chips. With the "plain" board, you can replace the 16F690 with selected other chips and continue right along. The big determiner is the inputs to the chip (VDD, GND, etc., vary from chip to chip).
The 690 is a very versitile and powerful 8-bit chip in itself. The fact that it is portable in the "plain" system makes it even handier. You can program it to your liking using the development board, then remove the chip to your working circuit, plug it in and keep going. It features all the perifrials, including ADC, EUSART, PWM, three timers, etc and runs well on its internal 4MHz osscilator.
And, as has already been mentioned, by using a breadboard and a 5-wire connector, you can program virtually any chip in the Microchip 10, 12, 16 and 18 families.
I have been using the Pickit2 "plain" version as described for over three years now, and have had very few problems of any sort. I do both assembly and c language and have used examples of most all the chips from 12 thru 18 successfully. I reconmmend it.