Grand convention. Convention is done every two years, on the odd years. VLS is done on the even years. Convention is a different location everytime. At convention the voting delegates vote on a variety of things. There are also seminars for the non-voting delegates.
Chapters usually send their President and EVP. I'm not sure if the advisor is paid for by the chapter but usually an advisor for the chapter attends as well. International officers also attend. The chapter President is the voting delegate. Some chapters can send quite a few girls where others just send their voting delegate.
When convention was in Phoenix in 05 a lot of Phoenix alum attended, mainly because it was easy for us to attend. :D
It's our 156th convention (because we've been around for 156 years).
Any other questions. Feel free to ask.