Although there are a few actual campgrounds in the Buffalo creek area, there are also quite a few designated dispersed campsites along the road. They are clearly marked and were pretty full on a Saturday of Memorial Day weekend (but what isn't?). There's several creeks that run through the area and a network of trails that intersect the Colorado Trail and the road. The area is popular with mountain bikers.
It was completely snow free when we visited for Memorial Day, and the creek was flowing high. There were some fish in the creek, but nothing big enough to catch. We chose to park at a designated parking area and hike a short distance on the Colorado Trail to camp. We found a nice spot that had clearly been camped in before as there was already a fire ring.
Overall, lots of space to camp and play and a good option for the shoulder season when higher options are under snow.
This area is a good (free!) alternative if the campground close to Shelf Road are full.
Turn on Road F24 and drive past the private property (well marked). The first larger camping area is about 1.7 miles in. There aren't really separated sites, but there are a few picnic tables and fire rings. Also, there is one metal shelter should the weather turn on you. We had a lot of tents and were able to find flat spaces for all of them. There is also a couple (fairly clean) pit toilets and trash cans. You can stay up to 72 hours. There was only one or two cars there when we arrived late on a friday night in spring.
The area also has some really cool rock formations - but only to look at unfortunately as they are on private property. However, there are plenty of rocks to scramble up on for a view of the formations that are public. Cool pinon, sage, and cacti nearby with the occasional mule deer wandering past.
If the first picnic area is full, there are more campsites further along the road.
We camped here during the winter while the car camping in Great Sand Dunes national park was closed. It's about 10 miles from the park and the view of the dunes and the valley is gorgeous. The road in is a little bumpy, but sedans were definitely able to make it.
The campground doesn't have a whole lot of trees and some of the sites are close together, but in the quieter winter season we had plenty of privacy. Campground has pit toilets, fire rings, tent pad, picnic table, but no running water.
The nearby hike to Zapata falls is worthwhile too, especially in winter for the giant ice sheets in the canyon.
We camped here in the winter when several loops of the campground were closed. Although it was the middle of the week and there were only about 10 other groups, the close spacing of the sites and lack of undergrowth still made it feel like we were right next to people (especially when RV generators start early in the morning).
Even in the winter, the toilets were open. The website listed potable water as being available year-round, but none of the wells or spigots were running when we were there.
In the morning the view from Moraine Park is outstanding, it's an easy place to start for a day hike in Rocky Mountain National Park to beat the crowds, and we had a herd of deer walk right through our site, which was cool.