It is what you want it to be. There is nothing wrong with wanting to just watch her. There are all kinds out there. A little patience and research and you can certainly find what you are looking for.
To answer your question, when we started, we thought we wanted to do the traditional swinger thing and just swap partners. There were times when we switched on and off but mostly it was her and the other guy and me and the other girl. We may have been in the same bed together but typically didn't do a lot of switching back and forth. There were times when the other girl was bi and the girls would also play with each other. My wife is bi also.
The very first couple we hooked up with I found myself wanting to watch my wife and the other guy way more than I was interested in the other lady. I had to be aware of paying attention to her so that she would also enjoy the experience but found myself frequently distracted by what was going on with my wife. I found this was the case most of the times we hooked up with other couples.
As we became more experienced we became a little more selective with choosing couples. As we did, it started to become more difficult to find a four way connection. There were a number of times where I was into the girl but my wife wasn't into the guy, or vice versa. Or maybe one of the other couple wasn't into one of us. It just became a little more work finding the right couple. Or sometimes having 4 people involved made scheduling a little more difficult with most having kids or jobs. We found with couples synching up schedules was more of a challenge.
After a stretch where we weren't very lucky with couples, we had a single guy reach out to us on one of the swinger websites we used. Single guys reached out often but we just ignored them. This time, it sparked her interest so we began to communicate with him. A short while later we were meeting for dinner and drinks which led to a hotel room and our first MFM. It was amazing. I was able to focus on my wife and seeing her be pleasured and give pleasure was exhilarating. She also enjoyed performing for me. We ended up meeting this same guy regularly for about 6 months before deciding on trying with another single guy. We found it much easier, less messy, and, as it turns out, more fun for us both.
We still occasionally would meet couples but our preferred arrangement is with a single guy. Oh, and we have always been same room. She feels safer with me in the room and doesn't think she could relax enough to enjoy it if I wasn't there. For me, I am a visual person so I like to see with my own eyes.
I hope that answered your question. Feel free to ask me anything. I love sharing the stuff. You can DM if you would like.