Well, we actually stay up in the preserve only because we have research permits to stay overnight, but IMO, the nicest "decent" place to stay near Monteverde is
here . I stayed their twice and it was very nice. Book a bit in advance because it's not a HUGE place, but they usually have rooms. I haven't been their since 99, but it's about as good as your gonna get if you want decent hot water and decent smelling rooms.

The food's good, too. HTH.