Yes, Switzerland. You haven't been there and train travel is THE way to go.
I took each of my kids there at age 13.
In Lucerne, walk to the Dying Lion Monument, then right next to it is something called Glacier Garden (Gletschergarten). In there is a walk of mirrors that distort your body, and a mirror maze where you literally can't tell what's a mirror and what's the pathway. EVERYBODY walks thru it with their hands out in front of them to try to figure it out. Kids (and adults like me) love it.
Then tell your son you're going to Rivendell. Yes, Lauterbrunnen is the actual inspiration for JRR Tolkien's Rivendell.
Take these easy hikes: Mannlichen to Kleine Scheidegg (best one), Grutschalp to Murren, and First to Bachalpsee. On a rainy or misty day, visit Trummelbach Falls (Google image it), a 45 min walk (or quick bus) from Lauterbrunnen.
If your son likes camping, look into www.camping-jungfrau.ch , where you can rent a trailer.
If you fly into Geneva, consider climbing the bell tower in John Calvin's church, and look into the free bike rentals to ride along the lake. (see www.geneveroule.ch)
My kids are now in their 20's and they are returning with me to the exact same places this summer.
Allen