Hybrid Bicycles - Need help comparing bikes, complete newbie

Hey, I'm 19 years old, and have never purchased a bike before and I was looking to buy one this summer. I would use it mostly just for exercise and some commuting, and just to ride around for fun, so I figured a hybrid would be the right type in case I wanted to go on some paths or whatever. I went around to my local bike stores, and the models that they recommended to me were the Trek 7.2, the Specialized Sirrus, and the Fuji Crosstown. Knowing little to nothing about bikes myself, I'm not really sure how to compare them even while looking at the specs. I'm planning on going to each of the stores again tomorrow to try test riding each of them, but any additional input would be great, especially if you put it in layman's terms, as I will likely not be familiar with typical bike lingo. Thanks!

Tire width can sort of be used as a proxy for how off-road-worthy a bike is. The Sirrus, for example, is really a pavement-only bike. The skinny tires are an indication of that. The Trek, otoh, reminds me of my son's Kona Dew. I'd probably be willing to take the Trek 7.2 onto easy singletrack, and certainly onto fireroads and old logging doubletrack.

Suspension is another thing to consider. I don't like suspension on hybrids. It adds weight, and you've got to deal with brake dive, which can throw you off balance and is just one more thing to think about that I'd rather not think about when I'm enjoying a ride. Plus, the suspension forks on hybrids tend to be low-end.

My current "hybrid" is a rigid bike having 38mm slick tires. My most recent ride on the bike began as a toodle around town on pavement. From there, I hit an old snowmobile trail, then back to pavement, then an ATV trail, and then two-track road, and then and ATV trail again, and then back to pavement. I put "hybrid" in quotes, because the bike is really a steel mountain-bike frame that I've hybridized.