Here in Colorado, many of USFS campgrounds have goodly space between sites. Some are tight for other reasons, ie, getting around trees/rocks/boulders, but the sites themselves are well spaced. We've found some real hidden gems in USFS campgrounds, and with my geezer card, I get to camp for half price! $20 for 2 night camping is definitely worth it!
In our immediate area, one of the hidden gems is Bellaire Lake near Red Feather Lakes. There's also Dowdy and West Lake in the same area. All have electricity sites available, and you're not on top of your neighbor.
Also in the Poudre Canyon west of Fort Collins, there's good camping with plenty of space between sites, both for boondocking as well as electric sites. Another hidden gem in the upper Poudre Canyon area is Ranger Lakes on the west side of Cameron Pass. Electric sites and LOTS of privacy -- and it's rarely full, except during hunting season.
These are 2 of my go-to areas for when I don't want to travel far but want to have some privacy.