Lots of GCAers will tell you that they don't use yardage devices or that they pace everything off or that they use bushes/natural features. This thread makes me wish Melvyn was still an active poster!
When Ballyhack first opened, there were no yardage markers of any kind anywhere on the property. The first round I played there was devoid of any such assistance and it was a blast. If you play any competitive golf, though, or if you just want to know a more precise yardage during recreational play, a distance device can really come in handy (and can do a lot to speed up play).
I used a SkyCaddie SG4 (older model, single color display) for a number of years. It was nice knowing yardages to the front and back of green sites (and the movable "target" allows the user to zero in on a particular pin position). As others have said, this requires a subscription and the device must be charged (mine had to be charged between rounds). Every now and then, you may have trouble connecting to GPS satellites and mine required me to download a course before I played it. When my subscription ran out, I had the few courses I play most often loaded on the device, but it erased itself the day after my subscription expired!
Because I had a gift certificate (and because I was tired of paying the annual fee), I picked up a Precision Pro Nexus range finder. It's lightweight, doesn't require a subscription (or connection to GPS technology), and gives distance (to 1/10 of a yard!) to just about any object you want. A nice feature is that is indicates how much battery life remains; this seems like a no-brainer, but many models don't and I've known lots of players whose batteries have died in the middle of a round (or golf trip) with no warning at all. It's also much easier to figure cover distance to bunkers and other features when you need.
My device doesn't account for slope, and I don't want that feature, but you can find it in lots of models. That extension is generally non-confirming, however, for tournament play.
Another benefit of the laser (versus GPS) is that it can make practice more productive (since you're able to establish distances to targets on any range or facility).
I use a printed yardage book for maps of greens and other notes but I'm generally referring to it when waiting for others to play. It can be a great way to record topographic information, contours, whether a shot plays longer or shorter than expected, etc. It's also a great way to know green depth if you're otherwise unfamiliar.
There are apps that combine many of these features, but I find that they guys who use them tend to do all sorts of other things on their phones during the round, too.
I think all of this impacts architecture in a major way. The modern designer must anticipate players who have a wealth of information, which can negate lots of visual effects and illusions that had more effect as recently as a couple of decades ago.
Hope this helps.
WW