I've been having the same dilemma with deciding when to bring in the orchids.
It's mid-70's during the day and drops to low 50's maybe high 40's at night. i've been leaving everything out so far on a very sunny porch (that heats up well with the sun). maybe i should bring plants in? my Angraecum sesquipedale and Rhynchostylis gigantea both started spiking right with the onset of cool weather / shorter days.