by BRIAN's suggestion of Honfleur is a mixed blessing. It's a beautiful town and in a great holiday area but it's considerably further than an hour from Calais, more like 3 or 4. It's in Basse Normandie (lower Normandy), but if you fancy going there, it's just accross the river Seine from the seaport of Le Havre (ferries from Portsmouth go there).
I know several nice towns close to Calais:
-Wimereux is on the coast and is a bit like a smaller version of the town below. It's close to the Caps-Gris / Blanc-Nez clifftops, from where you can see the White Cliffs of Dover.
-Le Touquet-Paris-Plage is a popular resort favoured by wealthy Parisians. It's a nice place, maybe like a cross between Eastbourne and Sandbanks with some added Frenchness chucked in. There is a good fish market, a sunday general market, a long promenade and a huge sandy beach that is used for horse-racing. There are lots of good restaurants. Because it's a bit posh, accommodation could be pricy, which leads me to...
-Etaples: a smaller town than Le T and its neighbour. It is also close to the sea but is actually on the River Canche's estuary.
-Finally, Montreuil-sur-Mer, which despite its name is no longer at the seaside because of falling sea levels. It is an historic walled town with very pretty mediaeval narrow streets and a nice central square. It probably couldn't be more French if it tried. You can walk all the way around the fortifications and see the views of the pretty countryside. Despite its inland status, the above two towns are within easy reach by car.
-Other towns that I've heard people staying in but know nothing about are Hesdin, Berck, Hardilot-Plage and Beaurainville.
All these places are about 30-50 mins down the A16 Motorway from Calais (southbound direction towards Paris)
Hope I've helped :D
Having just submitted my answer, it seems you now have 2 recommendations of Montreuil. Go for that!
My goodness, Christiane, you're very negative about those places. Well, I suppose there are two sides to every coin. I for one think both my and other's suggestions are 'excellentes'.
I have been fortunate to travel around France a lot; a family friend used to own a cottage in a little village close to all these places. Bon voyage!