Jamis looks more suitable to me of the two, which by the sounds of it seems to be your decision. The Bianchi might be ok for the 7 mile commute, but would be painful on a longer ride. Looks like more of a 'grocery-getter' frame to me - not something you'd want to spend too much time on.

Any reason you're not considering a bike with drop handlebars? E.g. something like a Bianchi Volpe or Jamis Aurora? The drop bars are much more comfortable on longer rides, as they offer more hand positions. Just something else to think about before dropping down your hard earned cash... The Volpe or Aurora really give you the best of both worlds - wider tires for stability, rack and fender mounts for commuting and touring, and the ability to take even skinnier tires and be used essentially as a road bike.

Tires... I'd at least give the 700x28 tires a go if I were you. I commute during the summer on 700x28s, and switch to 700x32 knobby tires for the winter when there's a bit of snow and debris on my route. I used 700x32 slick tires on my previous commuter, which was a Giant hybrid similar to the Jamis Coda. The bike was fine for my commute (about 12 miles), but changing to my current bike (Surly Cross-Check, a lot like the Bianchi Volpe) with drop bars and 700x28 tires made a huge difference to my comfort and speed.

Adjustable rise bars - in my opinion, you're better off asking your LBS to work with you to fit the bike perfectly to you. Get them to try different stems on the bike until you find the rise and reach that fits you perfectly.

Another one I'd consider... the Bianchi Castro Valley. Looks like a pretty decent starting point for a commuter bike to me. Single chainring (42), 11-26 9-speed rear, dynamo light, fenders... if your commute isn't too hilly, could work like a charm. Cro-mo fork with 700x28s gives a nice, smooth ride around town, too.