Haha just saw the smaller part of your answer, sorry about that. Given the choices you are looking at, I would say Hollywood Hills and West Hollywood. Totally depends on what you tend to like to do... but those would be the most fun and nicest for your age, I would imagine. Beverly hills is of course really posh and lots of shopping but older vibe. Hollywood is super gross in places, unsafe and overall just not worth it. So many better bars or fun activities in other places.
Hollywood Hills is beautiful because the hills are beautiful and you can hike, etc. And you can drive elsewhere to hang ;P But not great for walking. However, if you are in the hills around Sunset blvd. west of Fairfax, it's a great combo of posh nightlife, very LA classic urban feel and fun wacky things, coffee, food. Not the most walkable and charming but still 100x better than Hollywood proper.
As for West Hollywood that's also the other best choice. I would say the #1 best of your options. It's a thriving gay community in most areas, so if that's good or bad for you, you may have to take that into account. Great neighborhood areas, little parks, tons of food and bars, etc. Seems like a fun place and there is always something going on. Plus, it's central and easy to get to many fun neighborhoods around it.
