I agree with the earlier suggestion of tall t-shirts. They are just longer, not larger. I'm 6'2" and 200 lb and found that regardless of the type of pant, they slip, but the tall t-shirts have solved that problem for me.
I'm a nursing student and have been a loyal Mac user since '85! My advice is not to worry about iPhone compatability with PDA software for nursing. Get yourself a PDA now - it will be an invaluable tool in whatever you are doing. As for the iPhone,...