Visiting Jordan either as an extension to your Israel Package or as a separate tour is well worth considering. Some refer to it as "The Other Holy Land" because there are a number of Old Testament sites in Jordan, not to mention some stunning places that have to be seen to be believed.
At the top of the list for every visitor to Jordan should be Petra. Petra is the red rose city and there are no words to describe it. You need at least one, and possibly two days to do real justivce to the site. Among its most famous sites is The Treasury building made famous by Indiana Jones, althoug many films have been made in Petra.
Jordan also boasts a fabulous desert experience at Wadi Rum. The desert goes on for miles and really helps us to understand something of this area of the world. Lawrence of Arabia was here often.
The Madaba Map is another must see. Made in the 6th century out of over 2 million bits of coloured stone it shows an understanding of the area at the time and has Jerusalem labelled as "The Holy City".
For Roman towns, you can do little better than visit Jerash. Jerash is an incredibly well preserved place and allows you to think about what life was like under Roman rule in the MIddle East as most towns were built to the same specification.