I am looking for destination for a long weekend for me and my girlfriend, travelling from London. We want some place authentic, by the sea, with good food, not too crowded or touristy and easily accessible from London by plane.
I was in Bonifacio, Corsica 2 years ago and it would like something with the same sort of relaxed but genuine feel. I'm thinking possibly southern France or Spain.
Most coastal destinations in Europe will be crowded into September. A three hour flight means getting to the airport a few hours early, taking the flight and getting to your resort at the other end so can take up a good part of the day, and you only have a weekend.
Go across the Channel (I find the tunnel best) and spend the weekend in Le Touquet and surroundings.
[ Edit: Edited on 12-Aug-2012, at 04:30 by Cyberia ]
Have you thought about Dubrovnik, Croatia. Super romantic.
I second zaksame's recommendation. There should be a more-or-less direct flight available to Dubrovnik, and it is a very romantic place with rich history and culture. The climate in September should still be fairly pleasant, and it should be a little less crowded since the "high tourist season" ends in late August (well. at least officially).