I have used big gym personal trainers, personal trainers that had their own small space that only they used and I have a sister that did a few sessions with me at my home. There were pros and cons to each. I think having a personal trainer when you are getting back into it really helps with the motivation and education, and are generally a good idea for newbs.
Big Gym trainers: Pros: It helped me get comfortable with the gym I was planning on continuing to attend after I was done with the initial set of sessions, and it got me into the habit of going to the gym. Plus, they gave me a permanent discount on my monthly fees and waived my start up. The trainers themselves were a little cheaper than the average. Cons: Yep, they try to sell you their supplements. They aren't to pushy about it, though. Also, my personal trainer ended up going back to school and I had to switch to a new trainer. I don't see a huge amount of turnover at my gym, but many of them are students. Of course, since there are so many trainers, it's easier to schedule when I want to be scheduled.
Personal Trainers in their own space: Pros: They tend to know their shit, but I imagine you really don't know what you are going to get. I went to a group of girls that focused on women. They were really good about helping you track nutrition and goals, without trying to push products on you There was sometimes one other person in there being personally trained, but there were never problems with random people stealing the equipment you are trying to use. Cons: Unfortunately, that also meant you had to get a separate membership if you ever wanted to do anything on your own. Since there were only 3 of them, and they were good at what they did, scheduling time for sessions could be difficult. They were also about 30% more expensive than the big gym trainers. If you are going to go this route, I strongly suggest you shop around and find someone that focuses on the goals you want to achieve, since there are so many little things that may or may not be included in your training. These ladies did a lot with diet tracking since one of them had her graduate degree in that.
Sister: She was cheap as hell since she was my sister, and she was also new. She came to my house to train me, and usually bought minimal equipment. Some trainers will come to your house, but only if they are just out of school. One problem I had was with equipment. I had a few weights, so most of my training was done with stretch bands, balls or 5lb weights. I prefer to lift, personally, so this kinda sucked.