[Conqueror]

I've got a couple of pics, where essentially the sky is non-existant, its uniform white/grey. The subjects are both buildings/architecture and at an angle, filling most of the frame, except for the sky which in the corner. Shoving a graduated filter makes it look a bit more interesting, but its also apparent that's a PP addition and so not so natural.

Any ideas?

[mattb123]

I underexpose when I take the shot so the sky doesn't blow out and then boost the shadows in post to even it out.

[normhead]

Having an interesting sky to start with is a prerequisite. If you aren't seeing detail that was there when you shot because everything is bleached out, burn it. If it's totally zapped and there is no detail, you can always close in a better one from somewhere else.

[Conqueror]

The sky takes up perhaps < 20% of these images

Unfortunately the sky is often rubbish here... grey/white and/or overcast

[mattb123]

Long exposures with a ND filter is likely to make them more interesting if that would work with the rest of your shot.

---------- Post added 04-02-15 at 03:54 PM ----------

This shot would have had a pretty flat white or grey sky with a faster exposure but at 15s it gets a little more interesting.

[EarlVonTapia]

Having an interesting sky to start with is a prerequisite.

Yup

Clear blue skies might make for a good day of shooting outdoors, but you won't be taking pics of the sky since blank skies and seamless clouds are generally boring.

Seek the clouds!

[wildman]

I've got a couple of pics, where essentially the sky is non-existant, its uniform white/grey.

Post them

[abmj]

If you are ok at post-processing, it is possible to replace the sky area with a better one. Rather than explain it here, I'll include a link to Matt Kloskowski's tutorial. As he explains, it starts at the 42:10 mark in the longer video.

TIP: Watch My Sky Replacement Tutorial Free | MATT KLOSKOWSKI

[dms]

If the sky is not a wide expanse on wide FL lens, a PL filter may help to reduce the DR. I use it a lot w/ my Pentax Q.

[adwb]

Select the sky part only and add a grad or as suggested change it for another from your library of sky shots, you do have a libery of sky shots don't you?

[photodesignch]

Cloudless sky, you need color!! Wait till golden hours.
Cloudy sky, correct exposure is your friend. Clouds can make image more interesting.

[6BQ5]

Skies can indeed fall flat if they are grey to begin with or too bright. Try creating a layer in your PP software and burn in some shadows around what could be clouds. Adding copious amounts of contrast and some saturation in that layer could help too. If there aren't any clouds then try a gradient as others have suggested.

[SpecialK]

Perhaps go B&W?

[MPrince]

Take two images. One exposed for the subject, one exposed for the sky. Read this article to learn how to blend the images: https://luminous-landscape.com/digital-blending/ A tripod is useful when doing this, makes it easier to line up the images when blending.

There are other techniques. I use Topaz Labs ReMask when blending.

If you shoot raw, you can sometimes recover the sky from a single image by masking the sky, putting it on a separate layer, and change the layer mode from normal to multiply, adjusting the opacity if needed.

You can even replace the sky with a completely different sky, though that may not always look natural.

[Kerrowdown]

How to make the sky more interesting?

This is where Photoshop can be a friend to you...