I live in Wyoming and I too freak a bit with tornadoes (I FINALLY used to be fine with them...then last year, my husband had to go out of town and of course, the first day he leaves, I hear the sirens. Well, I turn on the weather channel to see what is going on and nothing...I listen for my weather radio to go off and nothing...my friend calls me and asks what it is about and I look out my east and west facing windows- I live on a prairie so nothing for miles!!!- and see blue sky and sun, so I tell her to just keep an eye out and to turn on the weather channel...our town will sometimes turn on the sirens for other things, like flooded roads to get people to go inside which takes the emergent out of them...stupid, I know! So I decide to let the dogs out quickly in case a storm was coming and sure enough, I go to open the door to let them out, take one look at the funnel cloud that is south and hightailed it downstairs with all the kids!!! Apparently, the police officer who called the funnel into the weather station gave a local landmark and the national weather station couldn't figure out where that landmark was (we have an area we call "the rocks" on the wyoming/colorado border...which is only 5 miles south of our house!!!!), so the only warning we got was the local siren...my weather radio NEVER went off! Scary, huh?!? On top of that, the cell towers overloaded with the mass of calls that came at once and stopped working so I couldn't even call my friend back to tell her that there really was a tornado! Luckily it moved west of my house at an angle away from town, but totally freaky! We had 3 more reported that night, but luckily my parents live in town so they came to "rescue" me and the boys and we slept at their house that night!)
We have a full unfinished basement (so I have 2 windows to worry about...luckily they have metal around the edge so I put up blankets over them with strong magnets to help keep glass from flying everywhere if they break). Every year, I stock our emergency box with water, snacks (granola bars, crackers), diapers/wipes or whatever the kids are in at the moment, toys/games, first aid kit, battery alarm clock (in case we need to sleep downstairs), comforters and pillows to pull on top of us, a chair for the youngest kiddos to be strapped into in case I have to run back upstairs for animals or whatever, flashlights, extra batteries, whistle and all our information (names, DOBs, emergency contacts/ph#s, blood type, important medical history). I have my weather radio upstairs so I try to think to grab it when we are under something and have considered getting a small wind up generator/flashlight/radio to plug things in if I need to in case of power outage. We have an area between our two sets of theater chairs in the center of the basement that we duck in...but if it got really close, I'd head under the stairs more (really near to our ducking area...I figure if the upstairs floor caved in, it would hopefully be caught on the two theater chairs or the uprights for the stairs would protect us some (though as I have researched today, someone brought up a good point...watch what furniture- heavy couches, fridges, dressers- are on the floors above you because if the floor collapses, those are coming down too, so it may change where I put us downstairs!)! We use the comforters to wrap around ourselves and over our heads to help protect ourselves from debris. I agree with the carseats and helmets too, but unfortunately, I don't have enough for all my daycare kids! I make sure the kiddos have lots of toys/puzzles to keep them busy and even have our portable DVD player that I put downstairs if I suspect something is coming so the kids have something to watch if the power goes out. This year, I even invested in some glow sticks/necklaces for the kids to help them not be so scared if the power goes out! For the dogs, I put a larger kennel downstairs that they go into when we go downstairs....keeps them from running all over the basement! We also have a tv hooked up to cable downstairs that is far away from our area but that I can still see (in case it "explodes") to keep abreast on where the weather is!
For those of you who do not have basements or in apartment buildings, here is a suggestion... I have it worked out with my neighbors who only have a crawl space that they can only access from the outside but are elderly and can't really crawl in well, that I will leave my house unlocked when we go downstairs and they can rush over to my house and let themselves in (I'm usually the one who contacts them all when we are under any type of severe weather watch/warning so they know if I am home or not). I have the same thing with my friend who lives a few blocks away in a trailer- in fact, she has a key just in case I am not home for some reason as trailers are almost as bad as standing outside during a tornado and I never want her or her kids stuck at her house! So, you should knock on the lowest level's apartment, introduce yourself and see if you can trade shelter for say, some cookies...:-)! Then when the storm comes, you have a safer place!
As far as your locations in the basement, find out where the majority of your storms come from (ours with severe storms usually head from the south/southeast), so the southeast corner would be the WORST side to be in, so other than that, the basements is about equal!