The ultimate environment for meditation?

The practice of shavasana at the end of an asana practice is a part of the practice of pratyahara, or withdrawal of the senses.  In our modern world we are generally bombarded with sensory stimulas, in the form of a sea of people each with their own facial expressions and body language to process, advertisements pasted on every inch of available eye-level real-estate, ear-buds in our ears blaring the newest dub-step, and constant movement of our bodies though an artificially constructed environment.
This over-stimulus over-stresses

This leads to an imbalance in the sympathetic nervous system (or tension or concentric movement) relative to the parasympathetic (or relaxation or eccentric movement) and makes us, in colloquial terms, 'stressed-out.'  This is why we often want to slow down our movements in yoga, for things like kick-backs, so that we can engage the parasympathetic nervous system through controlled relaxation of our muscles.  This is the 'flow' part of vinyasa, utilizing the eccentric part of the movement to slow the movement down and keep the vinyasa under control at all times.

If some of these words (eccentric, parasympathetic) are not in your vocabulary then you should probably be doing more reading on physiology.

Another way to combat over-stimulation is to withdrawal from our senses, to disengage our mirror neurons, and focus inward onto our own body and mind.  This is pratyahara. For meditation, I often prefer to lay in shavasana a la yoga nidra rather than sit in lotus. I have some posture issues, namely upper back cross syndrome due to excessive computer usage ::cough:: which I am working on, that make relaxed seated pose not all that relaxed.  As such, I read with interest an article on the use of dark, quiet salt water tanks for floating to induce maximum sensory deprivation.

Essentially, the therapy entails floating in a shallow, warm salt-water tank in a darkened room with ear-plugs in.  The idea is to completely shut down all stimulus to the sensory system and thereby force you to focus inward onto yourself.  The text describes the author's somewhat mystical experiences, which understandably are not uniformly positive! This particular place is located in Portland, OR. Some quotations from practitioners,

“Normally my head is several different radio stations playing at once,” explains tattoo and comic artist Levi Greenacres. But in the tank, he found relief: “With the lack of sensory stimulation to intake and compute, I discovered an inert state of un-ness, the need to think, feel, and feed completely abolished. The quiet in there is total comfort.”

and,

“After floating I feel very open and calm, and less prone to distractions,” says illustrator Natalie Phillips. “The better I feel emotionally or physically, the better I am able to focus.”

Sounds interesting, especially if paired with the practice of meditation. Meditation is part of my practice that is definitely a work in progress.  I struggle with sleeping and have my whole life. I often feel like my brain is 'fizzing' away like an alka-seltzer tablet fired through a meat-pie.

Oh, you haven't heard that metaphor before?  Here's the visual evidence:

As a sub-clinical introvert, I am just a tad overstimulated thanks to the combination of internet and high population density.  Being solitary in the woods is something that's been wonderful for me as an introvert.  This floating technique sounds promising as well.

Has anyone out there in cyberspace experienced this?  Any thoughts?