Escape 100k and 1million as per the above comment, they give more long-form runs. Also how about a kill the ender dragon run, or even a kill all bosses run (dragon, wither, elder guardian, warden)? All of these would require at least a little bit of planning ahead, and gathering natural resources to get geared up (looting can be disabled for all of them solely because its impossible to tell what is pre-planned and what is not, even though it would make it more interesting). I would add all advancements on here but the two phantom advancements are impossible and How Did We Get Here is extremely difficult to get.