You literally dock in town in Nassau - just walk off the ship and walk through the tourism offices and into town.
Here is the info I used and then what we did:
http://www.tripadvisor.com/Travel-g147416-s410/Nassau:New...
See the straw market
For a great lunch - walk down Bay Street towards the Hilton and stay on Bay Street to the Arawalk Cay area. Just down that way, on the beach side, you will find tons of pastel colored shacks that are local restaurants. Amazing food, good drinks and great prices:)
Fort Charlotte (could take it or leave it - I've been to St. Augustine)
Parliament Square and
Queen's Staircase - we got to see an awesome exhibit about the Queen's Jubilee since we were there in November of last year - and it was still going on. Didn't plan on that but it did add a lot.
Consider Governor's House.
We did do a lot of walking and at the end found a bar not too far from the ship and had a few rum punches.
We went to Royal Caribbean's private island: Coco Cay for our other stop so I can't tell you about Freeport. The beaches in Lucaya are supposed to be very nice so maybe figure out if you can walk there or grab a taxi to get there rather than spend so much dough on an excursion.
Good luck! C.