I drive 450 miles each way to Road to California each January. I drive 8 miles to Tucson's local show each January (sometimes twice) if it's not the same weekend as Road2CA. I drive 110 miles each way each March to the AZ State guild's show in Phoenix/Mesa every March.
Last year was the first time I took Amtrak to CA (450 miles each way for only $38 each way) to see Long Beach. I'll probably try to go each year for that too. Road2CA and Long Beach are the only National shows I've seen. Oh, I saw NQA in CA 15 years ago... Does NQA still move each year?
Most of the time we're going with relatives - 3 or 5 of us. I love talking about the quilts with Mom, my sisters, and Eddie. I also love seeing shows with less experienced people to see their sense of wonder and awe - it's usually different than mine. Almost always though, I like some personal, alone time to walk the show by myself.
I was the Treasurer of the AZ State guild for a few years - I think in the late 90's we were getting 4,000 visitors. I'd guess Tucson gets more than 1,000 but less than 5,000... I don't know if there's anyone on TQS from the Tucson guild that could give you better numbers.
The internet - I get all my information about quilt shows, both local and national, from the internet, specifically the guild or show's web site.