Every Caltech student I have known says that CalTech is like drinking from a firehose, esp the 1st year. Most of them say it is both overwhelming and exhilarating. You know your daughter: is that her?
Every JHU student I know is a very hard worker. JHU students do not tend to see the weekend as time off, but more time to work on what they are doing. It is intense but a steadier pace. You know your daughter: is that her?
My guess is that no matter which one she chooses, she will need a year between undergrad and med school to get in the ‘extra’ stuff (volunteering/shadowing) that med schools are requiring, but that is becoming the norm.
eta: here is a thread on taking time after college to prepare for med school: Is it a good practice to take a post-grad gap year to prepare for a med school? - #11 by WayOutWestMom