Ok, I don't want to attract the wrath of any Fresno-lovin' people, but I did want to add my viewpoint.
I've never been to Fresno itself, so I can't comment on the city - that wouldn't be fair. However, I have been to other nearby Central California locations such as Bakersfield, Tulare and Visalia a few times. When I think of that region of California, I think of the phrase "middle of nowhere". It seems so flat, brown and uninteresting. Like CarolinaCutie, I too noticed the lack of trees. Drive along the southern stretches of the 99 for a while - it's kinda surreal.
On a related note, my car once broke down on the way to San Fransisco. Where did it break down? Firebaugh. That has to be a grand prize finalist for the Middle-O-Nowhere awards.
Anyway, CP2000, just make sure that your sister understands that she's not going to be "near" the ocean or something, k? I think that a lot of people have an image in their mind of what California should look like - Fresno won't fit that bill at all.
Try looking at these websites if you haven't already:
http://www.ci.fresno.ca.us/
http://www.fresnocvb.org/
.....Kelly