No fishing license need at the State Parks as long as you're bank fishing, if you're in a boat though you need to have one a precautionary measure as the park boundries are 'fuzzy' when on the water.
We stayed at GRSP in November and had a great time. The sites were a little closer together then we like them but there weren't very many people so it worked out fine. The trails down to the water are beautiful and fishing along the bank of the river can be breath-taking.
Enjoy your anniversary!
~Snuz