Mont St Michel Away from any holiday time is a winner. A few nice small hotels on the mont itself, very little to do except relax and watch the tide come in and out
Salzburg is not too bad in the off season, or Graz though it suffers from inversions and can be cold and foggy if the conditions are wrong.
Really off-beat would be Bad Radkersburg, fly to Graz and catch the train from the airport to the Slovenian border.
Fontainebleau – 50km south of Paris. Easy to get to – Eurostar to Paris then hop on a local train to Font.
Beautiful, romantic small town – fantastic Palace, gorgeous formal park, lots of lovely little streets and restaurants, the best chocolate shop, and surrounded by a beautiful beech forest for romantic strolls 🙂
Someone mentioned Florence, personally I hated it – massive tourist trap.
If you’re flying, places I’ve been to for for a weekend with the wife:
Oporto is nice for a weekend, reasonable eating on the river, run-down charm, boat trips and a visit to one of the port cellars. Lisbon is also good for a weekend.
In Spain, Seville and Granada are great, Madrid, Barcelona…
You could always take her for a romantic wander through the war cemeteries and trenches 😎
We actually went with these guys and they were really good. travel company they do plenty of different breaks. we thought it was prety good value for money.