I would love a full modernization of the old DDs, honestly. I LOVE solo POTD, but all the bosses except 50, 100, 150, 180, and 190, are so boring. If you know the mechanics, there's just no execution required. Give them cool mechanics! Just pleeease don't touch 180 because it's such an iconic boss and a rite of passage for anyone who wants to be a Necromancer. Also, know how we sometimes find the spirits of people we've faced before? How about we get something like magicite from silvers to bring back allies from the dead, ala Aitiascope? Make silvers exciting to find in POTD.

HOH is almost there, but they should tighten the AP sync to make the lower floors more challenging, and make the the auspice buffs last way longer! Either that or make them more common.

EO needs a lot of work. Reduce the HP of basically everything except bosses. Reduce the damage of almost every oneshotting mechanic by 90%~ or so, so it can kill you, but can survive it with steel, stoneskin, etc. Crank up the auto attack damage of allllll the non-boss enemies, at least 30%. Also, just completely throw out the crystal layout. They're hideous and the visual obstruction doesn't play well with the mechanics. Lastly, do a pass through all the telegraphs. Keep the mechanics, but make them more visually digestible. For example, an egg enemy that does a frontal cone, and often passes over branchy terrain, shouldn't need its targeting circle alone to see which way it's facing.

Other than that, yeah, checkpoints, challlenge logs, etc, sounds great.