How well or poorly you do out west is largely dependent on your carrier. Apparently, FECC leans towards TVAL freight when trying to find loads, and will let a dry van sit. For my carrier, that's not the case. It's clearly not the case with vans.
I've been out west many times, and have no problems taking a load out there. I've gone out there and then gotten loaded back to the Midwest within a few days, and I've gone out there and spent weeks or months. One time I was out there for three weeks total and did really badly. I think it was something on the order of 900 loaded miles for the three week period. All the other times I've done fine. I spent the last two weeks of March, all of April and half of May out west of the Rockies. There were times I'd sit for 3, 4 or 5 days, and then get two or three 700-900 mile runs back to back. Overall I was averaging more than 2000 miles a week. Back in the middle of September I took a load to Mesa, AZ (where it was 112 degrees, sheesh) but the next day got loaded back out to El Paso, and the day after that delivered another one in San Antonio. I have an aunt in Green Valley who was not pleased with me getting loaded back out so soon, tho.
Back in August my AC compressor went bad. Works while I'm driving, but not so much when parked or even at a stop light. Figured, well, we've about got Summer knocked out, I'll replace that in the Spring. Since then I've spent one day in Indianapolis and 6 hours in Appleton, WI, and all the rest of the time I've been in places like South Carolina, south GA and AL, Tulsa, OK City, New Orleans, Miami, Houston, San Antonio, Laredo, Kingsville, Victoria, Brownsville, Uvalde, Del Rio, El Paso, Phoenix, Nogales... many of these several times... give me a break. It's really nice here in San Antonio now, finally. Low 70's for the high today and tomorrow, mid 40's overnight. But I could use a little Coeur d'Alene or Provo right about now.