help_pls

Hi all! First, thank you if you are reading my post, I really really appreciate it! So right now I am between two programs to complete my PhD in the sciences: PIBS at University of Michigan and PMI at the University of Pittsburgh. I am having trouble deciding because Michigan is hitting all of my requirements for the academics/research, but I am nervous of getting out of my comfort zone to be in a new city for 4-5 years. On the other hand, I am currently finishing my undergraduate degree here at Pitt and am impartial to staying for that reason and being certain that I have the chance to conduct quality research. However, my current boss at Pitt wants me to complete my PhD in his lab (he's a nice guy, do not get me wrong) and I know I would like to see what else is out there, but the pressure of being in his lab again is turning me off to the idea of going. I also do not know if it is frowned upon to stay at your undergraduate institution for higher-ed? I am not sure if anyone is in the same predicament or are in these programs but I would appreciate any guidance that can be given :-) thank you!