We stayed at the Marriott Marina and enjoyed the stay. Request a room in the tower with a view of the Port - vrs a garden room that overlooks pool area. We enjoyed lunch at the Tiki Bar and just relaxed.
What to do? You could take a water taxi or taxi to Los Olas and walk around the shops - quite interesting. Also lots of nice places to eat. If you have time, there are two companies that do water tours of the FLL area. You get to see some really expensive homes. We find this a relaxing trip. The boats have airconditoned spaces as well as the outdoor deck area. Check out
www.greatlocations.com - River Tours or Carrie. Avoid the jungle Queen!
If you need sodas or last minute stuff, you can walk to grocery store from the Marriott.