Former CM from the 90's. It's still magical for me but to be honest I always get so excited before I go that I expect there to be a choir of angels singing and a golden light, perhaps some weightlessness as I float through the gates and it never quite lives up to that as I step into MK. It's actually often a let down since I expect it to hit me in a big wave as I see the castle but that never quite does it for me.
Usually sometime within my first day I get an overwhelming feeling of - I'm here...I'm actually here. Then I get a little lump in my throat and pretend I got some dust in my eye. Usually it's the smell of POTC that does it for me...sometimes it's the taste of a Mickey Premium bar. I never know where or when, just that sometime it will wash over me that I am back "home". If I ever do a full trip without that feeling I think I would be done.
Knowing more of the ins and outs just makes me a better "tourist". Though to be honest - other than skipping backstage at points to get places faster it's no more than what many of the savvy people on here do. You just know the best times for attractions, the best spots for fireworks and the pleasures of taking time to soak it all in from your favourite attraction to the tinest details.
I'm less rushed now as I travel through and I focus on different things. For me it's photography and my upcoming solo trip for a conference will include 3 or 4 extra days for me to wander alone, probably do only my select favourite attractions and take some great photos, sit on park benches while people watching, take long lunches and do things in a manner that I can't when I bring newbies or the rest of the family with me.
It honestly does all depend on the person - I was a Disney nut before I was a CM so it enhanced my love for Disney and I had a solid background of at least a dozen vacations from '76-'95 before I worked there so I already had a sense of nostalgia for the parks. I worked with a guy who wanted Disney on his resume, never saw any of the animated movies, never went to the parks other than work and only ever went to PI on Disney property. He had free passes to the parks and I don't think he was ever in an attraction there - he worked, got drunk, went home - that's it. It takes all kinds.