The problem with playing the game you want is that it's a tricky balancing act, one person without the right mindset can throw you all off, and even if everyone wants the same thing, if you try too hard, you'll fail. Fantasy is like mystery is like beauty is like magic is like zen. The most you can do is be open and encourage finding that sweet spot.
So the first thing you'll have to do is make sure everyone wants to. I'd hope everyone felt the way you did, but if someone was only in the right state of mind after a root beer float, I don't know what you should do. It's awfully pretentious to suddenly tell a friend and long time player that his more casual, detached mood makes you not want to play with him. Hopefully just drag him in along with you.
Second, this doesn't start at the table, it starts a long time before that. Start looking at things in a new way. Take a different route to work, make it a point to catch the sunset, or if you really feel up to the task, live your life to a movielike extreme. Smell flowers just because. Keep a random sketch journal. Anything to keep you from falling into a mundane rut.
Read things and spend time with people who force you to think in ways you'd never expected. Keep track of how these make you think, and try to keep your thoughts in those patterns while you game. It'd probably push you close to the Chaotic side of things, but when you think and write like a work of art, it does things that three orcs, or even three greenish-gray, pig faced muscular humanoids can't do to you.
And when you do game, use props and setting to be as evocative as you can. Don't overdo it, and don't be cheesy. (After all, you do stand the risk of making it feel like just another round of dice chucking, only with candles and potpurri and bad nature music in the background if you don't keep things right.) Run things from a stream of consciousness, don't be afraid what anyone will think of you, (and in this case, have a standing rule that anyone breaking the mood or mocking a player for running with the mood has to sit out a sesson {in-character mocking is fine, but making the other players feel self-conscious kills the whole experience, and the smug player isn't much of one to help anyways,}) and don't be afraid to try something new. I'm pretty sure you know everything out of the books backwards and forwards, but if the monsters and spells are cosmetically changed, all of a sudden they can seem new, at least for a little while.
And above all, when you feel the sweet spot coming on, just keep doing what you're doing, don't analyze it or do anything to snap yourself out. Like I said above, it's something you can't really pick apart, you just have to experience it and revel in it.
