You say it is the two of you. Just curious, will it always be the two of you Young and close to starting a family? Or way past that. You don't have to answer on the board...
If it is just the two of you. heck if the two of you grow to a family of 4-5 or you have 4-6 folks over for a meal sometime I would say 99% of the time the 18.5 will be more than enough.
you can fit a lot on the 18.5. Plenty for meals for 2 or a small family or group.
I just bought a
WSM myself. I had all the same debates. I did get the 22.5 but I have a family of 5 and plan on using it more for larger family events then I do for quick meals for the family. Knowing that I would tend to use it for much bigger groups I went with the 22.5. Also at the time I could get $50 off the 22.5 from
Amazon so it was just a $50 difference.
regardless of my choice, again for you the 18.5 should be plenty.
Is there a Home Depot by you? reason I ask is at least where I live the Home Depots have the 18.5 on display so you can at least see the size of that one. Also they sell 22.5 inch grates for
the kettle grills etc. Not quite the same as having a side by side comparison of WSMs BUT you can at least hold it up and get a sense of the added size.
not sure this helped but hopefully it did