Anza-Borrego Springs State Park is a true California gem. We spent four days there and didn't want to leave. The park is well-maintained with friendly, helpful staff. The location is nothing short of amazing. Desert meets mountains. The weather in January during our visit was mid 60's during the day and mid to high 40's at night.
The town of Borrego Springs is a short bike ride away and very bike friendly.
They offer full hook ups and dry camping. We tried 2 nights of each. Our preference was the dry camping. The dry camping sites are nicely spaced and the area is quieter and darker, making for better night time star gazing. Anza-Borrego is a Dark Sky Place.