We tried ten days in our CCD 22 and it helped us think through wants and needs for a full-timing Airstream. First, wanted bigger fridge than three cubic feet. Second, really wanted a sofa -- didn't like only seating was the bed or the dinette bench. Third, wanted separated shower/toilet/vanity instead of wet bath. Fourth, wanted outside storage lockers.
Decided upon a 2005 CCD 25 and never looked back. It has been perfect in every way for two of us as we enter our fourth year of full-timing. We sleep over 350 days a year in it, we tow approximately ten thousand miles per year, and try to find somewhere warm to park and live in it for winter months.
A comment on suggestions for bigger trailer -- several times a year we are rewarded for having a relatively petite trailer. Some older provincial and state and national parks have small spaces. Sometimes a smaller space is the only available when we arrive. We fit just fine but others left it for us because their unit was too large. Also some older campgrounds have very tight road configurations, and we are able to navigate them more easily than any larger trailer. And anyone in a smaller trailer could do better than we, but this 25 suits us perfectly.
Like Paula said so well, checking floor plans is fine but you really MUST step into them and talk yourself through where everything goes and what it would be like to move around in it.