At the low end, just about anything graphical you can buy from Adafruit is supported by their in-house graphics library and display-specific drivers. They tend to be Arduino-centric, but if you know C++, you can strip it all down to the basics and port to any platform you want. At this point, you have graphics primitives (lines, boxes, ellipseses, etc.), as well as support for images, so design your GUI, code your event handler, and away you go.
A slightly more expensive option is the line of displays with built-in graphics controller from 4D.
If you want something more GUI-centric, you're probably better off stepping up to emwin or the like, on a Cortex M. Get a demo board with LCD and play with the examples. If that combo suits you, just look for a panel with an interface compatible with the micro (which will be readily available).