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.