My friend did the OU coed tour. Frum, kosher (not necessarily mehadrim- I’m not sure, but she doesn’t only eat mehadrin anyway so she didn’t mention it), apparently amazing. I wouldn’t do it in a million years (I wasn’t old enough when she asked me and this year I no longer qualify) but for the right person it’s apparently unbelievable.
One thing that did seem amazing about that kind of a trip is that they specifically invite Israelis to go along with the trip and give participants a taste of Israel. One of the Israelis on my friend’s trip was actually a married guy with kids living on a hilltop in the shtachim and I actually went to his house with my friend for a Shabbos- a really good opportunity to experience a lifestyle I might not have otherwise.
Another friend’s brother and sister-in-law are actually going to be participating as the resident Israelis in a chareidi couples Birthright trip (yes, this is a thing).