Here are two new ones which have surfaced since I started this thread.
Convenient Resort (great name!). Newly-built 4-story hotel at Lat Krabang, about 5-10 min. drive from the airport. 1000-1200 baht.
SP Powerlodge New entry on Lat Krabang. Basic rooms, no pool. Price of 1300-1900 includes 2-way airport transfer.
By consensus, on other forums I've posted on, the Sananwan Palace gets the best rating. Everybody who's stayed there seems to love it.