I have the 22.5. I only have myself and the girlfriend to cook for, and so it's plenty of room. One consideration is the bigger the unit, the more fuel you will likely have to supply it with.
If I could do it all again, I might go for a smaller one, but I am extremely happy with what I've made so far. So if I am ever entertaining, I have plenty of room to make lots of delicious food
The ribs were the best ribs I have ever had.
In doing the research I did, general consensus seems to be that it is the smoker to get for first timers as its generally easy to use.
When I made the ribs, I made the mistake of letting the temperature get too high before closing off the vents so I had to wait about a half hour with all the vents closed for the temperature to get back to that sweet spot of 200 to 250 F.
One thing you might want to invest in is a really good meat thermometer.
Using the advice on the WSM located here (
http://amazingribs.com/tips_and_tech...ain_setup.html), I bought the Thermapen and it was delivered to me from the US before the WSM shipped from Home Depot.