you didn't say who your current company was..
I know a few months back this company was needing something in Nevada
Western Staffing at 1-888-764-0067
No idea if they are good or bad, never spoken with them.
Also Try Fastaff.. The last email they sent me with listings (01/08/2007)
has ICU, SICU, Trauma ICU, Medical ICU, ER, Tele, MS, and more
I have traveled with them before and have never had and issues. Don't know if they are at the hospitals you listed but worth a shot. Maybe you can at least get one in Vegas.
good luck to you