I'm flying from Seattle to Tel Aviv in April and get one stopover pretty much anywhere in Europe I want.  I'm open to revisiting old friends (like London, Paris, Amsterdam) but also open to new or long-time-no-see adventures (Rome? Athens?  Prague? Other?)   Criteria:  - Lake/River/Sea  - Gardens/Palaces/Cathedrals (touring, not praying...) 
 - Lower costs are good. (Cost will dictate length of stop: 1,2,3 or 4 days.) Any thoughts yea or nay on possibilities are appreciated :-) Phil NOTE: Barcelona and Geneva/Zurich are off the table due to very recent or upcoming vacations with spouse.
You could do either Prague or Rome. You can get non-stops into Tel Aviv from either. Either city has reasonable accommodations if you research the housing websites. Both cities are worthy of more than a one day stop.