There is a wing spar STC which can extend the life by at least 7500 hours, the sooner you do it the more extra hours you get. I've done it on one of mine and now she's good for another 20 years..Not sure if it's approved everywhere yet though.
The PA38 is roomy, comfortable and has excellent visibility. You're not squished up against your student which doesn't make for an easy learning environment. It's not easy to fly, you have to use your hands AND your feet properly. I've got 3000 hours in them and never had an issue with the trimming so not sure what that is about. It's good to be able to look around the engine compartment too and teach the studes what all the bits and pieces are and what they do. In my experience studes go solo quicker in the Tommy than the Cessna.
Interior plastics are easy to fix and cheap to replace. Just go to
www.planeplastics.com and click on the bit you need.
There are plenty of threads about the relative merits and the nonsense about PA38s that was spread around in the early days, and perpetuated by people who have rarely if ever flown one.
As for the C152, horrible uncomfortable cramped hot things and visibility is terrible. All you can see of the engine is the top of the dipstick. UNless you are very thin with very short legs they can become a torture chamber after a few hours on board.
But then I'm a bit biased!
Each to their own!