IMO - not being judgmental, just an honest opinion - forget overnights and just book as many normal hours as you need.
I get how an overnight could seem attractive to those seeking to experience an additional layer of intimacy, but I really don't think paying a WG to sleep next to you is the answer. The fact you have even asked this question shows you recognise that the whole exercise fundamentally wastes time - and therefore money.
Know from talking to WGs that they generally just see overnights as a golden ticket, easy money from (quite often) lonely men who tend to be much more in need of a gf than a whore (not mugging you off, I'm arguably in this bracket myself! just telling it straight).
If you want to chat, fool around and enjoy a hot girl's company for hours on end - book a girl all day? It's just a smarter decision. You'll get the intimacy experience without worrying about setting multiple alarms/pissing money up the wall.