We've made that trip but in a sailboat. Your biggest challenge may be the stretch from Sandy Hook south to either Delaware Bay or the Chesapeake. It took us just over two days to get from Sandy Hook to Norfolk. After that it's ICW all the way to Florida. We've always gone outside around Georgia, too much skinny water. We've also never done the ICW between St. Augustine and Miami, too many bridges.
With only two of you I would recommend getting an autopilot, especially if you do any overnighters outside like Sandy Hook south and around Georgia.
Getting into and out of Long Island Sound requires a little bit of planning with the tides but we had no problems with the sailboat.
If you're interested, check our web site, www.svescapades.net
, click on 'Ports O'Call II', for the details of our trip south, it starts with the heading NYC.