When we were looking to buy a C-Dory, we went to the Seattle Boat Show. Back in 2006, the factory had every model on display at the show. I was thinking: 22; we spent a lot of time crawling around that boat. We then looked at the 25... it is significantly larger; much larger than the 3' difference might have to believe. More beam. More weight. Just more. I recall the discussions that the $30k difference in price (back then) was mostly about the enclosed head. It is so much more than that. You get more amenities: most of the 25s have a fridge, a full 30 amp electrical system, hot and cold pressure water (and a water heater), more storage, more beam, more height (6' 10" in the cabin), a bigger V-berth, bigger cockpit... and, yes, an enclosed head with shower.
Think that head/shower isn't important? Would you stay in a motel that didn't have a bathroom? We have spent up to 6 months at a time on the boat. Every night. In our case, that absolutely would not have happened if we had gone for the 22. For full disclosure, we have moved on (no longer have the CD-25), but not due to anything wrong with the boat.
The 22 is a great boat. The 25 makes extended cruising far more comfortable. On ours, we added a microwave, TV (cable and satellite capable), a shower curtain, a portable generator (Honda 2000i), full camperback, electric over hydraulic brakes on the trailer... it took us from the Pacific Northwest (Including being our "home on the water" while we worked for a whale watch company) to the Florida Keys. San Francisco Bay to the Erie Canal. New York City (via the Hudson) to Lake Powell. Yellowstone Lake to Desolation Sound. The trailer and a proper tow vehicle give you unlimited possibilities for couples' cruising.
For us, the difference between the 22 and 25 was like having a hard-sided tent vs an RV on the water. Again, no disrespect for the venerable 22 - many folks have had great adventures with those boats. The 25 was just a better fit for our use. Don't underestimate what additional "elbow room" can do for spending happy extended time onboard. The interior volume is something like 30% more on the 25 over the 22.
Performance wise, the 25 will give you a better ride (it weighs more than a ton more than the 22). You will pay for that better ride and stability with more fuel burn (bigger motor/hp) and the need for a more robust tow vehicle.
Good luck with the decisions.