NES and original Gameboy .. 20s.
My sister would routinely get into the 30s, way way way better at it than I was.
I can routinely break 250k points (3rd rocket). I start at level 7, and generally hit about level 19. I probably have around 25-30 tetrises. I play the original gameboy tetris. My legs usually fall asleep and I have to get off the toilet.
Sub an old thread but I've played the NES version several times in the last week.