I stay in them more often than I would like, and now that I've found my ED88T, it's not too much trouble to take measurements.
(Right now I'm in Costa Rica looking for affordable low-EMF locations.)
The Wide Mouth Frog Hotel in Quepos was a lot better than I expected: -50 to -59 dBm at night in the microwave/WiFi/GSM frequency band. I was in a private room near the office, so it's possible that the other parts of the hotel are farther from the WiFi base station.
The other place I've stayed is a house on the Barva volcano (which is inactive and hasn't erupted in 8,000 years). When the WiFi router was turned off, the signal strength in the same band was too low for the ED88T to measure.