First, in my opinion the Queue has the same importent level than the station if someone want to build realistic and/or create Re-Creations.
Second, not every Coaster in real has good/interesting Queue's, because some Parks haven't the space for it or want to save money. So they build these ugly maze style Queue's.
But one key to build interesting Q's is to try to interact these with the track/layout/theme.
Good examples for doing that are "Nemesis Inferno", "Nemesis" and "Black Mamba". You can wait hours without getting bored, because of the great look of the coaster and the vegetation.
An other good looking/interesting Q-Line are from "Apocalypse - The Ride", in fact of the three video-rooms on there way to the coaster and the heavy themed outside-area.
What scenary? Alot of different sets, the same as for stations. If you use more sets, you have more variety to create good looking things.
For flowers/vegetation, think about the guest-view-position. Don't place flowers on spots that noone can see from the pathway/queue (ok, we can see it in fact of the birdview).
As for other things, its all about practice and try again and again different ways.
Oh, and dont forget to use pathcovers, to create smooth looking Queues along the landscape
Lg Cheleste