Have fun guys.
We learned last Saturday out there that you can expect major crowds near the visitor center, and a traffic jam at the intersection leading down the mountain for the last half mile and to the visitor center. While the visitor center is a nice one, the rest rooms are the only essential thing about it. If you can make a bathroom stop before descending into Borrego Valley, you can skip the frustration at the visitor center and get right on to the flowers.
Bathroom opportunities before descending into the valley can be found at the (tiny) Warner Springs Glider Port, Warner Springs Resort (Golf Club, I think), or at Santa Ysabel.
There is a manned (womaned) mobile flower info station in a parking lot along the road in the valley towards the town square traffic circle in Borrego Springs, so you don't need to fight the parking/traffic at the visitor center.
Download the best flower info before you go, including a map of the roads in the valley so that you can get away from the crazy crowds of people near the visitor center and out into the valley and see flowers away from so many people. We think that Henderson Canyon Road might have a good display of yellow sunflowers. We foolishly skipped that road last weekend, and we regretted it later.
We love to end our trip by climbing up out of the valley to Julian for lunch and pie. Take Yaqui Valley Road (I think it's S3) out from the traffic circle and up the mountain to Julian for a whole different atmosphere. If you have trouble finding parking, go a couple streets behind Mom's Pies up at the gravel parking lot of the Catholic Church ($5 donation).