I just answered your other post, so I'll take a crack at this question. I'm assuming you're referring to VHF/UHF scanner frequencies. Interesting frequencies really depend on where you live, and what you find interesting. For example, some folks may enjoy listening to 2 meter Ham comm's, where others may be put to sleep by that. Living near a major body of water, fresh or salt, gives you a wealth of possibilities in the VHF marine band. Living close to a major rail hub allows the monitoring of railroad radio traffic. Any major city has it's own possibilities. As far as the antenna goes, I'd recommend a discone mounted high outside your house, if possible. Discones cover a wide swath of frequencies. If outside is not workable, an external antenna mounted in an attic is the next best thing.
This was my first post to this discussion thread, but when no one replied I thought this was the wrong place, so I posted again in the New User / Getting Started section. I wanted to delete this postt but there is no option for that. I do appreciate the extra info on frequencies.
I agree with bob550, a good all round antenna is the discone, have been using one in the shack for decades, relatively inexpensive, easy to erect, lightweight, and if you are a ham some will work on the VHF/UHF ham bands. Just be aware that different models will cover different ranges so look at the specifications before buying. On the other hand most discones are not optimal for shortwave listening as they usually cover from 25 MHz and up.