First off, while Lightroom is a fantastic program, it does have its limitations. Creating photos like the ones you linked might require some work in Photoshop to get the full effect. Photoshop supports reusable actions as well, which would make it possible for you to create an action that gives you this specific look, and reuse it over and over to create photos like this in a few seconds each. That said, here are some options with Lightroom:

1. Drop the Vibrancy setting a bit, and increase Saturation a tad.
   • The photos you linked seem to be saturated in some channels, while desaturated in others. They are not completely devoid of color, and they seem to have a spread of color, so I wouldn't use the split toning feature (which will literally reduce your photo to two color grades).
2. Push exposure up a bit, or push the brightness setting up a bit.
   • Most of the photos you linked look like they are close to being overexposed, but not actually overexposed. By increasing the exposure or brightness setting, you can get that high-key look.
3. Manually tweak the saturation and lightness of individual color channels.
   • Lightroom offers low level control over individual color ranges, such as reds, oranges, blues, violets, etc. you can selectively reduce the saturation in certain range, shift the color of one range towards another, etc. You should be able to achieve a wide variety of creative tone and color in your photos this way.