Fun lenses to accompaniate x100f

What an exciting adventure you're embarking on!

I'm not as experienced a photographer as some on this forum—I'll be following this thread with interest, I can't wait to hear what people say—but I have a somewhat parallel setup: X100V as my slightly smaller, 'don't-overthink-it' camera, X-Pro3 as my more deliberate option. The majority of my photos are taken outdoors, with my toddler providing an autofocus challenge that might be equivalent to your dogs.

On the wide end, I thought about the 10-24 but went with the 16mm 1.4 instead. I like primes, and I liked the close-focus ability of the 16 combined with the wide angle. I use it often for nature pictures, either close up or landscape, but I also use it for portraits. Chris Boland, a photographer I follow on YouTube, describes it as the perfect lens for taking "pictures of dogs' noses." It's a quirky lens with its own fun aesthetic—so, if you're approaching this in the spirit of "chill out," I think it's worth considering.

For the fast-moving-action option, I decided to go with the 16-80. I mulled and mulled other options, mainly the 16-55 and the new 70-300. But I decided that, in a chill-out spirit, I wanted a relatively light lens with WR, and one that, when it was mounted, would allow me to capture 'normal' photos, too, without changing lenses. (I prefer to only use one lens on any given outing.) There are a lot of different views when it comes to this lens, but I figured I'd just pick it up and give it a try for myself, then sell it if I didn't like it. Well, so far, I love it. I'm not a pixel-peeper, but to me the images look very sharp and well-rendered, and the ergonomics of the lens are excellent. It's lightweight, fairly small, versatile, and fun to use, and the extra reach has allowed me to get a few nature shots I would've otherwise missed while out with my kiddo. It's delightful to sit on a rock at the beach, let him play, and then zoom in and out and see what happens in terms of framing and the image. I know that this isn't really how you're supposed to use a zoom lens—it's lazy! But it works for me, and is relaxing and fun, and I've taken some genuinely beautiful pictures this way.

I also have the 35 1.4 (my favorite lens) and have just ordered a 56 1.2. But the 16 1.4 and 16-80 are lenses I've used that seemed relevant to your use case.