Networld + Interop in LasVegas, usually around May is usually pretty good.
They run an area with emerging technology and give tours and hands-on seminars of each of the demonstrated technologies. Lots of seminars on nearly every wrinkle of networking ... wireless to 10GigE, security, management, new product announcments ... I worked the show many times and always picked up a lot of good information.
Plus...it's in Las Vegas
If you're already employed in the industry, it's usually easy to get free passes (usually exhibits only) and invites to the hospitality suites.
Networkers is good if you work in a Cisco environment. Typically they offer free/cheap exams. There are several Networkers shows (every quarter?) around the country.
Then there's some Linux shows, Microcontroller shows, Microprocessor shows, Cabling shows ... something for everyone. Check the industry rags ot the rags' web sites for showtimes.
FWIW
Scott