I would also echo this.
2 bags x 70 lbs each. Versus $25 for 1st bag and $40 for the 2nd bag (50 lbs).
Lounge access - though not sure which flights OP is taking, some have only a 50 minute connection, and that's not a lot of time, especially if crossing concourses.
Boarding Group 1. This is super worth it on the second ORD-CUN flights - which are just a nightmare of people trying to carry on massive bags.
Priority Security. Probably not that critical but it helps out of MCI.