St Anthony are the tallest, largest dunes in North America and are about 5200 ft above sea level. If you have a forced induction engine, you'll see a minimal loss in hp, if it's N/A you'll see a 20% loss in power and an increase in engine temp. due to the engine working harder. The dunes cover a smaller area than Glamis, but are more fun. The dunes to the east are baby dunes, covered in scrub brush and interspersed with lava fields. The Sand Hills resort is farthest to the east, has the most grass in the campground but you have to travel though all of the scrub brush to get to the largest dunes all the way on the west side.
Idaho Dunes RV is dirt with cement pads next to the rigs and is located roughly in the middle of the whole area and the medium sized dunes start there. Idaho Dunes and Sand Hills both have full hookup. Egin Lake is a BLM campground and is located next to Egin lake, which is a shallow body of water people sometimes drive across. The last I heard, the BLM campground has no hookups, takes no reservations and is first come/first served.
The bigger bowls to the west are really huge and made of coarser volcanic based sand. It sticks together and if you push it right, you can make it "sing" or vibrate. Some of the larger bowls actually have lava fields in the bottom of the bowl, basically all of the sand is sitting on top of a lava field.
I've been up there 3 times and each time I spent about 5 - 8 hrs to get to Vegas, slept in Vegas and took off at 8 in the morning and arrived at Idaho Dunes at about 6 pm. I always took 13 day trips - 2 days driving up, 9 days there, 2 days back.
I think most people do July 4th and later up to early Sept. trips, IIRC, there has been snow on the dunes in late April/early May in the past. Summer days up there are long, with the sun setting as late as 930 pm. Even the nights are mild, with some of the locals duning late after dark and if they break down, they just party over night and get help in the morning. Everyone I met up there was very friendly, willing to help or give good advice. In the past ID Dunes RV has ordered race fuel for guests prior to their arrival and had it delivered to their camp spot waiting for their arrival. This was a long time ago, but I hope they still do it.
Hope this helps!
