Environment

[MANUEL_MOUSIOL]

sounds like it just needs tone mapping to lift the shadows and compress those highlights
why are you using a sun with HDRI - gonna look weird

some pretty cooked suggestions in this thread, 2 suns are something you might do in 1994. keep it simple, respect albedo / black / white values and it will look good

This cracked me up. 1994!
you are right of course but I have to disagree that it will look good if values are respected. Just because something is real doesn't mean it will look good. With photographs you might do a tonemappdd hdr image or even go in and light the areas that are too dark, by lights or by bounces. In CG we can fake it to help ourselves. Of course one would need to make sure it looks good as well, so the more you distance yourself from reality the more it will look fake obviously. But still: real=good-looking isn't always valid in my opinion.

[squintnic]

yeah no one solution agree - i cook the hell out my personal work to be fair - but when going for a straight up 'realistic' arch vis look the default values and approach can go a long way.
we still use a lot of vray sun sky to control where light hits and add a high res HDRI for relfection if there is loads of glass.

[glorybound]

I use a V-Ray sun with my HDRI to get sharp shadows. I don't mind dark shadows and actually prefer the contrast, but 90% of the time my clients ask me to brighten the shadows.

[MANUEL_MOUSIOL]

I use a V-Ray sun with my HDRI to get sharp shadows.

What HDRI are you using if you dont get sharp shadows? Sharp shadows can be accomplished with an hdri as well...

[glorybound]

I purchased many from here, but the site has since moved. I like these because I can use them in my scene as a backplate, too. Other HDRI's I can't do that.

https://hdri-locations.com

[piotrus3333]

as squintnic said: don't overdo it with silly outdated tricks. stay realistic. use all the adjustments within VRaySun first and if you can't get what you need than go further. set up the scene lit by VRaySun and than use it as a reference for lighting with environment maps as these are usually all over the place intensity and range wise.

lighter shadows with VRaySun:
this depends on the amount of sunlight scattered by atmosphere. use turbidity to control that. default 2.5 is way too low in my opinion. no city on this planet has air that clean.

environment maps:
either not enough dynamic range (shadows not dark enough) or huge glare streaks around the sun left on the map (shadows not sharp enough) - photoshop them out.
example with 1123 Sun Clouds v3. range quickly widen with reversed Highlight Burn in VFB (value above 1.0)