I've only ever used my sigma 8-16 for landscapes.... but who knows, it could work.
Here my 21 ltd.
Here's the 10-17 fisheye.
Here's the Sigma 8-16
Notice how the UWA shots help me emphasize the foreground over the background.
For everything in focus with people... a small sensor camera, in this case the Optio W90 but also a cell phone with a good camera.
Picking up puppy Tia (that's her mom in the middle of the dogs) with the DA 18-135 at 31mm. (Just in case you're wondering what the FoV of the 31 might be like. Even here, Tia's sister on the right is bigger than she is, in real life. I'm holding Tia. Even with the 31 on APS-c there will be some perspective distortion.
With the DA* 60-250 @250mm, almost no perspective distortion.
K-1 and DA 28-105 at 73mm
How much space you have is a big factor, which is why you need to get out with your DA 18-135 and get a feel for how far away you prefer to be and what FL might be suited to what you want.
Just for the record, on Aps-c I personally wouldn't like to shoot the type of image you propose at less than 50mm. Many prefer longer lengths for portraits, standing further away compresses the background, which can limit the distraction of a messy background, and maintains a more natural looking image, compared to how we see.