@esjliv that's a great point! Personally, I use very little data as I try not to be on my phone much so the $15 plan works great for me but I can see how it may not be ideal for heavy data users.
Unfortunately not all cities are listed, however, the city you select will not impact your account. It is recorded for PM's personal data/records. I would suggest selecting the city closest to you. Hope this helps!
I just switched over a month ago too and am also very happy with the change! It's great to have so much freedom at a lower cost as well as a community to help answer any questions you may have.