Just back from Eurodam, and we bought the Club Orange upgrade. The cabin upgrade was a crap shoot, as we had booked a guarantee. We did get an upgrade, but our friends who also booked a guarantee and did not purchase CO, got a better upgrade. The noticeable niceties included:
Priority boarding - literally zero waiting in line - and disembarkation - we got to leave whenever we wanted to.
A table by the window at every single meal we ate in the MDR.
The expanded menu included one additional entrée option that we were not informed of unless we asked.
The expanded room service menu included a no-charge mimosa and a couple of additional upcharge items. That's it.
We did receive the zippered tote bag, but IMO it would have been nicer to be in addition to the regular tote that everyone else receives.
Bath robe had orange piping instead of blue, and was the heavier type similar to those in suite cabins.
We did receive the glass of sparkling wine at dinner the first evening.
The "special event" was an expanded galley tour.
All this to say, CO likely made our experience much nicer - we were accommodated on every request of dining times and location, and spa appointments. We've not cruised HAL in nearly 10 years, and we were pleased that the wonderful service we remember is still there. Even if the free after-dinner espressos are no longer free.