I wish they had a comparison table that made easier to choose. I'll have to print out and put the pages side by side.
Also: do you know if it's possible to actually see the tents before buy?
Best place to see most of the models they make in one place would be at the Overland Expo, which is being held at Flagstaff this May. Depending where you are located in Cali it may not be that far of a drive for you and well worth to make up your mind on which one would be right for you. I went to the first 2 and it was very helpful to see all the different brands and make comparisons, being able to crawl up inside of them and try them on for size was great. The Expo is the best place I know of to do this and you will meet a lot of people there who have real world experience using them, I'am signed up for this years Expo and it looks like there is going to be a FJ Cruiser camping section this year.
Autohome does have a catalog that I picked up at the last Expo that I went to and it has a lot more info than the website does and is easier to do comparison between the models also.
The differences between the models are not that much but can be important. The Extreme would not be a good choice for you IMO because you have a baby and it only comes in a small IIRC and has the lowest roof height of all their models, it is designed for hard use which most people probably do not need and weighs more than other models. Airlanders are the most common, proven design and they have an ex. long version available. Airtops are fairly new use air rams for lifting which makes for a little bit more inside space since they don't have the sissor lift mech. taking up space. Other models have racks but are generally not that much different inside. The Columbus has good inside height at one end at least and super fast setup/takedown not that the others are slow either.
On a FJ Cruiser, the small would be the best size in tight 4 wheeling situation but the medium works just fine, more likely to rub things though. The large is too wide and the ex. long will overhang the roof some. Hope this helps you.