Best clipless pedals for distance or touring?

Those shimano pedals are great as they got more area to stand on than the original.

The normal XT onward pedals have slightly more area contact than the budget offering but nowhere near the trail one.

Someone modified their by cutting the useless bit off;

big fat +1 to decent mtb spd's.
Pretty much all road shoes are impossible to walk in. my house is surrounded by deep gravel, which makes the walk from the shed to the tarmac a royal PITA when in road shoes, nearly knackered my ankles so many times its not even funny.

Good old shimano you can rarely go wrong with them

Ditto, Shimano hybrids.....good to go....anywhere.

Prefer the M324 and no probs on flat side with Mtb shoes - had the single sided touring pedals (looked like the photo posted by smallfurry) but can be a bitch at traffic lights if the pedal spins wrong side side up when trying to clip in as no solid contact area to push down on ( however I guess your tour route will probably not take you through central London so probably less of an issue!)

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+1
I don't really understand single sided SPD's, unless its just a price thing? As the DX type platform with an SPD pedal embedded in it truely allows normal shoes OR SPD shoes to be used, without faff.

It's a weight thing.

Road riders, on the whole, ride with cleats so don't need the ordinary side, and unlike mountain bikers, aren't clipping and unclipping regularly so don't need double sided SPDs.

I'm a fan of SPDs and have single sided on my road bike, dual purpose on my tourer and double sided on my fixie (easier to clip in on the move).

^
+1
I don't really understand single sided SPD's, unless its just a price thing? As the DX type platform with an SPD pedal embedded in it truely allows normal shoes OR SPD shoes to be used, without faff.

I'm hoping the mallets I have will work like this. With the pins extended for flat shoe use.