A couple of inputs:
1. Our 37TB has a pullout pantry. Doesn't have the fancy french door refrig on purpose. When we upgraded to the Challenger, we really didn't need any additional refrig space but we did need the pantry space. Additionally, we have lots of basement storage space. In the compartment next to the door, I setup some of the molded storage units (from Home Depot) to hold some extra household items. Also, we carry bottled water in front of those selves.
2. Upgrades. We have at least two that are absolutely necessary (IMO).
First, an electrical surge suppressor (ours is built in). Keeps the coach from getting hit by a either low or high voltages. You'd think that this would be a standard item. IMO it is essential.
Second, a Tire Pressure Monitoring System (TPMS). IMO, sits right there next to the suppressor as a requirement. We have systems that monitor engine water, oil and gasoline. Yet the system where our wonderful coach touches the road - not monitored.
3. We added a couple of things that the DW felt essential niceties.
-A way to hold stove tops without breaking them. Found this over at IRV2.
Thor Challenger Owners Unite! - Page 119 - iRV2 Forums
-J Latches to keep some of the large storage bins closed.
- Air Compressor. I don't care what sort of RV you have, using the ones at truck stops/gas stations is a no-go. At best they are wonky (technical term for unusable).
-Rock guard. Lots of pro and cons to this one. After soon to be 12 months and 18,000 miles ours is important.
-Washer/dryer. We use our a LOT. The huge water storage (grey and fresh) makes feasible even when boon docking. We spent 2 months in Key West and will do 3 months next year boon docking. Go to a laundry mat a couple of times and you'll understand.
Hope this helps.