Absolutely drive the Suburban before you cross it off your list. As others have said, the cargo space difference is huge (plus you gain a bit more leg room in the 3rd row). We are in a 2014 Honda Pilot with 5 kids ranging from 10 to 2 and going anywhere with the whole family requires the roof top box. Before we placed our order (Yukon XL), our local Chevy dealer had a used '21 Tahoe on their lot. Salesman gave me the keys and told me to be back in a few hours so I brought it home and parked it next to the Pilot. The interior seating space comparison was a huge difference, but the cargo space didn't seem to be considerably more. Certainly it is, but thinking through all the things we bring on trips to the in-laws, vacation houses, camping, etc. it didn't seem like it would fit a lot more.
A quick google search says the '22 Telluride you have now has 21 cu.ft. behind the third row. The '22 Tahoe is 25.5 cu.ft. If you feel like the Telluride has no cargo volume right now then you're not going to notice 4.5 cu.ft. of increased cargo volume. You will notice the nearly 100% more cargo volume going to the 41.5 cu.ft in the Suburban.