The 940 / 939 spectrum analyzer seems to be pretty nice. Looks cool on youtube, is probably even better in real life.
https://www.youtube.com/watch?v=IZvQ5pcw7MA
https://www.youtube.com/watch?v=CGV4pq0u8Lg
There are just a few boomboxes with spectrum analyzers that I know of. The aforementioned Sharps, Sony FH models and this Panasonic RX CW300 (there's a RX CW200 with spectrum analyzer as well):