It says you have to end up 100 miles away. It doesn't say you can't land at airports and do stuff along the way to make it more "challenging".
Oh that's a lovely flight plan you have there... but I smell smoke... better put this thing on the ground somewhere... how you going to get down from up here? Is there an airport somewhere nearby? ;-) ;-) ;-)
Plus the long XCs tend to be designed to get you out of the local area you're probably intimately familiar with by the time you've got enough hours to pursue the Commercial, and more importantly, out of the local weather pattern.
But if your instructor isn't making you work at least a LITTLE and is just napping over there while you burn fuel in cruise, what are you paying them for?
The day XC to unfamiliar airports, if you do that a lot anyway, probably not a tough challenge. But weather can intervene.
The night one to unfamiliar airports can be very challenging, and if weather comes up, more. My "official" night long XC was to South Dakota and it was a no moon, overcast, and hazy night. I'd say even though the entire thing was legal VFR, I was on solid instruments for 1/2 hour with no real great ground references, but when we did see farmhouses and roads, we had perfectly legal VFR visibility and cloud clearances... not to mention the 40 knot crosswind aloft that night...
But if you want "challenge", I'm sure any good CFI would be more than willing to add some "challenge" to either one of them. LOL!