"How do we go about finding a partner for her? Juliette thinks it might be a good idea to go to an event where there are many couples."
These can be fun but they can also be intimidating. It matters on the event and who is there.

"I’ve researched some that are coming up in our area, and they could be interesting, but the flyers show younger, fitter people than we are."
If they are flyers, they are probably just advertisements. It could be that the people on the flyer are not even going to be there. They are models.

I went to a swinger event once and the only people dressed as Slutty as I was were the dancers paid to be there. Everyone (who wouldn't bother to talk to me lol) kept fixing my dress because my nipple was falling out. I was confused as to whether I was at a swinger party or not. lol

"I’ve heard that there can tend to be a mix of ages and body types at things like this."
Every single event I have ever attended was a mix of people. Don't be nervous. True swingers can tell whether someone who is heavier or older or slimmer or this that or the other will have a good sexual presence. Good sex is what the true swinger looks for. I have men who are 60, 63, 53, 46, 28 on my list and they are on my list because they turn me on.

"Should we take a chance and sign up?"
Yes!

"Is this likely to end in embarrassment?"
Only if you let other people make you feel that way. The lifestyle is about you two having fun. You might not meet anyone. If you go and feel sexy or use the event to dress inappropriately in public amongst strangers and then end up going home and having hot sex, it is a success.
It is rare for me to meet someone at these parties. I am too kinky for most swingers. But I can tell you that being dressed like a total Whore in front of people I don't know totally turns me on!!

"What about Craig’s List? I’ve heard some bad stories, and it seems there are a lot of no-shows."
Do NOT use CL!!!! I have heard bad and good stories but mostly bad, really bad.

"And what if she doesn’t like him?"
All email corresponding should include pics. True swinger males that are going to be all they promise to be will be willing to send pics. If they can't send pics, they are flakes, fakes and/or cheaters. (You will hear a lot about jobs and not being able to send pics. Move on and ignore them. We all have jobs. My favorite is a "job in national security" )

"I’ve seen a thing called Swing Life Style online."
I have used SLS in the past before I had a website. (My website gives me way better access to men who are as perverted as I am.) It worked occasionally for me. Remember, face pics, face pics, face pics or the flake ratio goes way up. There is a feature there that allows you to post pics that you can lock and allow only certain people to see. You should have pics also. Don't post unedited sex pics there though. I think they are owned by Alt.com and that company sells pics to other websites.

"Finally, what about me? As I said, I’m more into it to watch than anything else. How is this received in the swing community? If we go to a party or event, will everyone think I’m a creep? We certainly don’t want to make anyone uncomfortable."
It is a very common swinger thing. Everyone I know in the swing scene who is a couple considers men like you solid gold. Men who enjoy and relish their women getting off whether they join in or not are the best men in the swing scene. I always say yes to men like you. It means you are going to put my fun first because you put Juliette's fun first. Juliette is lucky.

If you have any other questions, don't hesitate to ask.
Piper