I've attended the HES the last three times they are here in the west coast (SF and LA) and am planning to attend this year as well. The show runs from Thursday to Sunday. Thursday has always been reserved for trade people only, and Friday - Sunday are open to the general public. Every year I would take Friday off and attend the show three days straigt, and still feel I need more time! There are just so many gears to listen to, and more LPs/CDs to buy. If the meet is onsite, I would probably check it out, but if I have to go to another location, I would most likely skip.
One-day/Three-day Tickets can be purchased in advance through Stereophile/Home Theater magazines for a discount, or at the door at full price. If you are buddies with a dealer/manufacturer, you could probably score a guest pass....