Hi Charlie! Welcome to MM's bulletin board!
Although I've never stayed in a hotel in Jaca, I've spent many vacations there (in a private apartment), and really love it. I hope you like it, too!
Jaca does not have anything like a parador. It has several hotels and "pensiones," and there is a new "casa rural," called Los Cerezos, just 2 km outside of town, that looks interesting. You can see pictures of the various hotels here: http://www.lospirineos.info/aragon/hoteles/jacahoteles.htm
The hotel that has traditionally been considered the "best" in Jaca is the Gran Hotel. You can see more here: http://www.inturmark.es/gransp.htm
One of the nice things about this hotel is its location - right in the heart of town, with the park in front. Others are also right in town, but this location is perfect. The Conde Aznar is just down the street, also in front of the park, and has a well-known(and more expensive) restaurant.
Several newer hotels have opened in the past few years that look pretty good. All will have simple rooms, in the style of the area - light wood, simple lines. I'm sure you'll find they are all spotlessly clean as well.
There is plenty to do in the area, and plenty to see in town, for such a small place. The nightlife in the summertime is great, and the bars, restaurants, and pastry shops are outstanding. Don't spend too much time in the hotel!
I hope this helped a little. Enjoy your trip!