If you are not fond of the fatter tires already, I really don't think you'll find them to be worth the "cush" factor later.

Yes, there is a trade-off with tire sizes... I'm speaking as someone who has 28 on one bike, 32 on another, and mtb slicks on a third, so clearly I like wider tires. (don't forget the joys of lower pressure tires, too! My 700x28 were high pressure, then I switched for lower pressure Vittoria Randonneurs and the comfort factor went thru the roof!)

I would be inclined to go with the Trek you know you already like.

"Beefier" looking frame doesn't necessarily mean anything. What really matters is how it feels. And "pretty" does matter! If your gut instinct is that a particular bike is beautiful, don't fight the gut! Get the bike that calls out to all your senses and makes your heart jump!

(If you do have a concern about a bombproof frame, how about trying steel? The Kona Smoke is similar to what you are looking at, but in a steel frame. I was gazing longingly at one of the 2008 Smokes today at my LBS. But it's hard to justify buying another one. Even when it's only $350. (I have a 2007 Smoke, which my son is using. It has smaller wheels than the 2008.))
www.konaworld.com/08_smoke29.htm