I'm 62 (male) and I take loads of day trips (on my own) all over Europe. (Paris, Brussels, Amsterdam, Copenhagen, Bratislava, Rome, Barcelona, etc, etc), so I might have been to a few places that you'd enjoy. However you've not told us what you like, so providing a decent answer might be a bit difficult!
Even so, one place comes to mind that's simply got just about everything that you might possibly want, whether that be beautiful beaches, fantastic architecture, quiet bars, vibrant nightlife, superb restaurants, fantastic shopping, wonderful historical and cultural attractions, an excellent fully-integrated public transport system, or whatever: Barcelona
http://www.barcelonaturisme.com/wv3/en/
So that's my top recommendation. However the Italian Riviera is also fantastic. (Fly to Genoa. Hop on the direct bus to the rail station and travel on the rail line, which hugs the coast, to Santa Margherita Ligure or Rapallo. The area is stunningly beautiful, while Genoa itself has a fantastic old town and offers excellent shopping opportunities.