My friend has an Iguana which I have ridden and also had it to my LBS. I liked the bike and the LBS guys spoke very highly of it. It was surprisingly comforable to ride despite not having a suspension front fork.

My LBS is a Trek dealer who only sells Bontrager. They have a nice online site that describes each of their tires fairly well at http://bontrager.com/products/components/tires

You might be interested in the H series (H2, H4, H5) or the cyclo cross XR series...

I would not get the cheapest 30tpi tires without any flat protection. But my LBS actually recommended against getting the other extreme, the "hardcase" tires because they are too hard to change. Some people go with a cheaper tire and add liners to protect against flats.

In any case, you may want to consider new tubes as well. I did the same: started riding a 20 year old bike that had sat for long time. I replaced the tires but found out the hard way that I should have replaced the tubes as well. You may also want to consider a spare tube and a portable pump that could mount on your bike (and a set of plastic tire irons).

I'm not technical enough to know what will fit on your bike -- but if nobody here has any ideas, I would check with the LBS or go the 'bicycle mechanics" forum.