If you are unlucky with the weather, then both Carneddau and Glyder plateau will test your map reading skills to the max, especially the Carneddau, whose plateau does not fall below the 3000ft contour for nearly six miles, and any discussion and de-brief can be talked about at leisure, at where the group went horribly wrong this side of Foel Grach.
My suggestion of a three day Welsh 3000ft summits traverse, was for favourable weather conditions, and in fine settled weather, you can almost discount using a map for the entire outing.
I agree, using map reading skills can be enjoyable and make a walk more memorable, but its the walk itself, that is of utmost importance, and if the vistas and scenery on offer are superb, its often best to see them in fine settled weather.
There is little enjoyment to be had to trudge through heavy mist and rain, only to realise the path you should have taken is a significant distance behind you.
There are areas of Mid Wales, especially around the Rhyader and the Cwm Ystwyth area, where a three day tough hike is a possibility, yet accommodation, especially for a group of walkers is poor to say the least.
The Brecon Beacons also rate very high for demanding terrain, and walks that can take several days, but my suggestion of the Welsh 3000s has both accommodation, and depending on phone network, good mobile phone coverage if things go wrong.
Accommodation for a three day 3000 summits traverse is never a problem, and the route covers some of the very best mountain scenery in Northern Snowdonia.
As for my location, i live in the shadow of Moelfre in the Rhinogs, in the small community of Dyffryn Ardudwy.
There are a few really tough three day traverses in and around the Rhinogs, but that would test the stamina of just about any seasoned walker.
No, if you want a three day walk, totalling only 38miles in total, but covering some of the most diverse terrain in Wales, some of it quite demanding then the Welsh 3000s taken at a leisurely pace, comes highly recommended.