My Wife writes Sci-Fi Books! Any good Conventions?

I thought this group might be interested. My wife happens to be a budding Science Fiction writer. We've been hitting up a lot of cons to help sell her books and get her name out there. If you want to check out her book, please do so.

Can anybody recommend some good conventions we could get a booth at? We're located in South-Central Nebraska, so anything in a day's drive or so would be great. (Hard to fly with all the book stock we have to bring with)