I know we aren't talking about a suburban anymore, but I remember the ones I was used to were really 'people movers' and the cargo space in the back was actually quite small. So there probably would be more cargo space in a jeep, it can only move half the people though.
I'll point it out again, the Yukon XL and Suburban are the same thing. One wears a GMC badge and the other a Bowtie, that's all.
In most configurations the Suburban seats 8, and with that I'd still bet the Suburban has more cargo space then a Cherokee seating 5. There are a lot of them around here, and they are quite long so that even with 2 bench seats in back there is lots of cargo area. Now, it you but a third bench seat in back, (which can be done) Then yes, the cargo area is only about 12" behind the third bench, but it can then seat 11.