Back when I was a kid, electric fans were very dangerous things, and kids often lost fingers in them: the blades were metal and the grates were large enough to put a hand through. Starting in the early 70's, standards for safe mfr. were developed, and nowadays almost all household fans in the US are fairly childproof. I think that the primary kid safety issues now are hair; (especially if a child knocks over a box fan and then stands over the back of it), and water, in terms of electrocution. Of course, fire is always the most common danger of all with fans, but that's universal -- fan motors can easily overheat, so you have to be vigilant about them, and also make sure that the cords do not get damaged. You shouldn't leave a small child unattended in the same room with a fan that is low enough to reach, even by climbing.
Ceiling fans are your best bet. If you have to have portable fans, I think that the tower-shaped fans may be a bit safer, as they don't have that mesmerizing vortex look that kids find so attractive, and the covers are usually screwed on rather than latched. Fans that are on stands are usually harder to tip than box fans, though really tall/heavy ones should be anchored with a toddler around. Be sure that whatever fan you choose has really small crosshatches on the covers; I'd say that if you can't get an ink pen in they won't be able to get small fingers in (though it won't help you if she decides to throw rice into it, as one child I know memorably did. Raw rice thrown at a fan scatters like buckshot.) For a fan with a more or less permanent placement, I'd consider bolting it down.
BTW, have you considered moving your A/C out of your kitchen and perhaps cutting a wall hole for it if you only have picture windows? Putting a room unit in a kitchen when you need it to cool other rooms is usually the least energy-efficient thing you can do, because the heat from cooking makes it work several times as hard. Most folks I know who use window units either don't bother to try to cool the kitchen, or they put a separate smaller unit in that room.