When does long hair look too long to be pretty?

I have very long ash blonde pin straight hair. It's pretty healthy since I don't dye it but I never know when to get it cut shorter to keep it looking nice. The hairdressers always want to only cut about an inch or two so I usually ask for a lot more just for a change though its still long even after that. Right now its down about my waist but I'm worried it will look messy being so long. I really like having it long because my hair is very fine so If I tie it in a bun for work its the smallest little thing and you'd never know there was so much hair tucked in. so my question is, when you see people with long hair how long is pretty, and how long is just overkill. you can post links to pictures to show your opinion if you like. thanks