First of all I want to let you know that only few days ago I took one of my last exams in Master's Degree in Architecture, so I'm quite familiar with what we Architects and designers like. :) We fall for the clean simple design. A few elements which say enough.
#68 - something very simple yet clen and rememerable. #69 - in case you search for something a little more comples. We've got the T letter for 'Texas' and the white lines which cross the star and resemble the 'A' letter for acces. Yet the white lines are layed out in a way to remind of a ramp. You certainly are familiar with the importance of the ramp as an element in the construction of the barrier-free living enviroment.