By using Priceline you saved a lot on the hotel -- just use some of that savings for a taxi. 37th Street is the dividing line between zones 2 and 3, so if you are a block or two west of there, walk to 37th so any taxi trip to the Hill-monument-museum area would be a two-zone ride costing about $10 (all of downtown from Dupont to the Mall to the Capitol is zone 1).

Just wanted to update this one for everyone who helped out.
Just returned from our trip and had a great time.
We used a combination of all of the answers here! The first day when our feet were still fresh we walked all the way into the mall through Georgtown.
The second day we walked to Dupont metro station. The third day we went to Rosslyn.
The main way we got around though was the new circulator line which stops every 10 minutes (give or take a few sometimes) in Georgetown and runs all up K St. to Union Station. We walked about 5 blocks back to the hotel from there through the wonderful neighborhoods of Georgetown.
The only other option which was very convenient was the GU shuttle. They have two line: one to Rosslyn Metro the other to Dupont MEtro. The Rosslyn has no other stops while Dupont stops a few places between.
We didnt use that much though because we enjoyed the walk through the neighborhoods in the evening. Did I mention I loved Georgetown?=) For $80 a night I would gladly stay at the University again.
Thanks again for all your help...a full report will soon follow as soon as I get caught up at work!