To help with size comparisons, I am 5' 5" with a 30" inseam, and ride a 15" 7.2 FX WSD. The seat post is at its max. extension, but the next size bike was a bit too big for me.

The 700 x 35 tires may seem skinny compared to a mountain bike, but they'll give you a nice, stable ride. I even cut across a field on mine one day when a road was unexpectedly closed on my regular commuting route, so you can actually do a little off-roading on them, if you're so inclined.

What drew me to this bike was its ability to "grow" with me as my riding progresses. It's comfortable and sturdy, which the newbie in me really appreciated, but it's also lightweight and sporty. Like you, I was not able to plunk down heavy money for a bike. The 7.2 FX was right at what I felt comfortable spending as a beginner.

I don't have any experience with Specialized, GT, or the other brands you mentioned, so I can't comment on those.