Portsmouth would be a great choice in any season. Lots of things to do and see; some pretty inexpensive or free.
near downtown on Islington Street has an awesome burger basket with handcut fries for 5 bucks.
Prescott park is on the harbor by the main bridge from downtown. Great water views of the harbor and Portsmouth Naval Shipyard where they refurbish atomic submarines. Plays and performances in the warmer months.
Nearby Rye and Hampton beaches, Wallis Sands State Park. New Hampshire's coastline is only 17 miles long so you can tell your honey your taking her on a New Hampshire coastal tour from one end to the other. Starts in Portsmouth and ends in Seabrook.
Just across the harbor is Kittery, Maine and some awesome outlet malls.
Jim Lee , REALTOR? http://jimlee.com
RE/MAX Coast To Coast Properties