For most ale yeasts (English, US) I primary in my crawlspace which is a constant 66oF-67oF. I wouldn't want to go much lower than that and definitely don't want to see it spike above 70oF. After primary, I will bring it up to ~70oF for a day or two, then rack to secondary and leave it at 66oF-67oF. Once I keg it, I try to get it as cold as possible (easy to do this time of year out in my garage) for a few days before putting it on CO2.
Lager yeast, I monitor like crazy! Primary at ~46oF-48oF until the krausen falls, then do a two day D'rest at near 70oF. I then rack it to secondary and let it get as close to freezing (~36oF-38oF) as possible for as long as I can stand it!
At least six weeks. I also am beginning to use gelatin to clear it in secondary during this time.
German and European Ale (Kolsch, Alt), Steam/Cali Common, I'll primary like an English or US ale yeast, but secondary like a lager.
Belgian or Saison yeast, I'll try and get above 70oF, especially if I'm trying to bring out any bubble gum/clove/banana esters. After primary, I'll treat it the same as any other ale yeast.
And if you really want to know what the temperature is inside
your fermenter/carboy, you need a thermowell
! That may be my next big purchase for fermenting lagers.