In your opinion do orchestras which usually play classical music symphonies count as amusement gatherings? Or are amusement gatherings generally more up-beat, party type environments?

Most people aren't usually attracted by that type of music anymore, even in the west. I would say the atmosphere is more akin to attending a theatre play (as opposed to an action-packed cinema screening for example). However, I'm not sure if this type of orchestra environment would classify as an "amusement gathering" or not. Many things are amusing, some haram some halal, but is an orchestra "amusing" in the haram way?

Such gatherings usually contain, in addition to music that carries the forbidden, dancing of semi-naked women, which leads to the forbidden view.

It is not recommended to attend such events.