I’ll second Bruges. Not far from Calais (an easy day trip if staying around Calais) and Bruges/Belgium is great if you want to get around the area by bike. As you’ve said, a lot of the WW1 battlefields are around the area, but very moving when you see the graves in the flesh (not the sort of thing to brighten up a holiday). Hill 62 is where most people go to see trenches and a small WW1 museum but I found it a bit depressing, I have to say. Montreuil is a lovely town and worth a visit if you fancy a wander around a typically French town. Victor Hugo apparently based Les Miserables on Montreuil and you can see why. They often hold open air concerts and plays in the summer. I’d also recommend Atelier 26 if you’re looking for somewhere to eat while you’re there. Le Touquet is worth a visit too. Massive flat beach (so big, you’ll struggle to see the sea when it’s out) with plenty of restaurants and bars, horse riding amd cycling. I’m not into golf, but the area’s apparently good for golf too. Expensive for the area. In general, the food is good (pork, apples, cider and fish seems to be their thing) and plenty of cycling but your view of the area will be weather dependant and similar climate to the south east, not surprisingly – can be rainy and misty. Not the best choice in France but enough to see to make a visit worthwhile. The further from Calais the better. The downside is that there”s quite a bit of industry there and quite a few places flattened during the war so not a place that attracts tourists, often with good reason. It can also be “rough” in places around the ports (as anywhere). I had a Bastereau lookalike try – and fail – to forcibly relieve me of my wallet in Boulogne whilst walking down a main street with my family. Avoid the big shopping mall places around Calais. Soul destroying, unless you’re into that sort of thing. If you want to eat near Calais, go a few minutes down the coast to Audresselles. It’s nothing to look at but there are some great little fish restaurants (the sort of slightly shabby looking places where the locals eat but good food – La Marie Galante and Chez Mimi being two but don’t look much from the outside).