Yes, you need to ride them all and decide for yourself. I can give you *MY* opinion on the bikes you've listed but that is just my opinion...
You need to find a bike that is right for YOU, and that fit's YOU.
I own a bike shop, and I help people make that decision all day long. I stress to them that all bikes have merit, and that you have to find the one that fits you the best, that "speaks" to you. I can usually help them find something in my shop, but sometimes it's a different brand. And that is ok. Like I said, all bikes have merit.
That being said, if it were "ME", and I had the choices you have laid out, I would go in the following direction...
Specialized
(prolly shouldn't go here, but gonna jump in anyway)
I would never buy a Specialized. This is purely from a bike dealers standpoint seeing how unethical their business practices are. They are very cut throat- even to their own dealers. In the past I had a Specialized road bike, and a mountain bike. So did hubby and son, but now that I have a bit of background, I wouldn't touch one. Do they make beautiful bikes? yes. That's the sad part. I guess it comes down to how you feel about things like that.
Again, your call. If the bike fits, it speaks to you, and you don't mind dealing with a company that has a "at all costs" attitude about business. Go for it. It's kind of like the anti vs pro wal mart debate in a way.
(I'm sure I'll get slammed for this, but I think people should know.)

Bianchi-
Sold them last year, very nice bikes. They are a niche brand though, and I've found that they either fit you like a glove- or not at all. I do love their wsd road bikes. Sexy sexy machines! - Too bad I didn't have the market for them because they are great bikes. One thing I did notice was the parts spec/price ratio was not as competitve as the major brands. Your "bang for the buck" may not be there. But they do have quite a pedigree. Dating back to 1885 in fact.

Fuji-
Pretty nice bikes, but they seem to have a dept store feel to them. Depending on the bike you can get a great deal. Did have some issues last year with performance selling people road bikes that were too big for them. They had very long top tubes for the size of the bike. So watch the fit on whatever you are looking at. Don't go by frame size alone.
In fact that advice should be used with all of them. Be more concerned with the effective top tube length.

Well, hope this helps. Like I said- find the bike that speaks to YOU. Because only you will be riding her. Not all of us online houligans!