CAS at Cornell is great for exploring a variety of interests. Both physics and economics are housed in that college, so you could double major in them or major in one and minor in the other.
How stressed people are at Cornell depends on the week. I have weeks where I’m super stressed and probably do not come across as happy to visiting prefrosh. But other weeks are a lot more laid back and less stressful. Any time you visit, it’s going to be somebody’s busy week.
I also wouldn’t say Cornell is less intelligent or less fun. Cornell is home to the most intellectual and intelligent people I have ever met. A lot of people also have a “work hard, play hard” mentality, so there are always fun events or shows or parties on any given day.