I never used my Commodore 128 in 128 mode.
Okay, so I did occasionally. This was very rare, however, because I always had the Epyx Fastload Cartridge plugged in, and this caused the machine to kick into 64 mode every time. I didn't have a use for 128 mode, except to run any software I had that was designed for the 128. Most of the software I owned was made for the Commodore 64, so I used the machine in 64 mode. All the time.
One of the nifty things about the 128 was the ESC key sequences. It was possible to create a "window" on the screen using the ESC, T and ESC, B combinations. One would position their cursor where they want the top-left corner of the window to be, and then would proceed to press the ESC key, followed by the T key (not at the same time), to define the TOP. This is followed by positioning the cursor to where the user wants to define the bottom-right corner, and pressing ESC, followed by the B key, to define the BOTTOM.
A simple program would define a window in which text can scroll, while not affecting the rest of the screen.
10 PRINT CHR$(147)
All screen output subsequent to this program being run will be limited to the defined window area. (Of course, you could always do a Run/Stop Restore and reclaim the entire screen.)