Hi Julie.I'm also 40 next year,in September and we just came back from Palma in Mallorca (I was checking it out for next year!) It's the nicest city I've ever been.Lots to see,beaches if you want them,great shops,bars and restaurants.Really clean...just beautiful.Can't recommend it highly enough.Almost forgot,lots of cheap flights available.We stayed in a gorgeous apartment but there are also loads of nice hotels.My dad and stepmum are coming next year as well as others of different ages.Have fun.