Content originally posted in LPCWare by NXP_Paul on Mon Sep 16 05:38:42 MST 2013
The LPC111x family is based on a Cortex-M0 while the LPC17xx family is based on a Cortex-M3 core. This is not usually a major factor when learning a new microcontroller.
The LPC111x family does have a much simpler peripheral set than the LPC17xx so in some ways that makes it easier to learn, however, you don't have to use the complex peripherals (Ethernet, CAN, I2S, etc.) so learning the LPC17xx doesn't necessarily mean you will have a more difficult time using the LPC17xx.
If your only desire is to learn using LPCXpresso with a simple microcontroller, then the LPC1114 would be a good choice. The LPC1769 would be better if you think that you may want to use some of the more complex peripherals, or if you need higher clocks speeds.