Oh goodness no! You don't pick your site until 2nd year! I would have ended up in very different places if I would have had to pick before starting school.
You get assigned to your rotation site through something similar to the match for residency. You have the opportunity to visit the various sites during 1st and 2nd year, as well as a Hospital day on campus when all the sites come to town and provide information in a fair type setting. When I was a 2nd year we had the opportunity to write a letter of interest to our top site. The site has the opportunity to pick half of their available positions from the letters they receive. The other half of the positions enter the lottery. You will list your top six sites you would like to attend. You will either be chosen by your letter to your top site or you will be matched based on the lottery. For my class 90% or so got their top choice. It depends on where you want to go and how competitive that site is.
For my class MI was one of the more competitive areas. For the class above me it was OH and for the class below me it was AZ. Its all dependent upon where people are from/where they want to end up.
I matched to a site in MI and have done all of my cores here. I love it and I would pick my site again. I did a mix of preceptor and hospital based, even though it is considered a hospital based site. I got a good amount of hands on, maybe more maybe less than my classmates at other sites. I was never the 4th or 5th person to get to do something, more like 1st or 2nd. During 3rd year you meet with your site coordinator and dean monthly. In 4th year you are much more on your own. For your core rotations they are set up for you for the most part, at least for me. For any and all electives its up to you to set them up, but you can go anywhere you want if you want to do the leg work.
I had a good experience with the school helping me with questions/concerns/needs for the most part. I know some of my classmates can't say the same. That would be one thing I would say to check out at potential sites...do the coordinators seem helpful and on top their game? It helps you out a lot as a student if they are committed to helping you out. Also, help them out! Make sure you're responsible, get your things done on time, if not early.
Medicine is a two way street from the day you start medical school. Help others help you and your experience will be that much better.
But for real....rotation sites are important, but I honestly didn't worry about it until end of first year. Know your stuff, do well on boards, then tackle the wards.