Twin beds are a great choice for guest rooms. You can accommodate two adults without forcing people to sleep in the same bed (which can be a bit awkward). The beds can always be pushed together to create a full size, if a couple desires more intimacy. Also, bedding for twins is relatively inexpensive to buy. One thing to consider before purchasing a twin is the length. You might want to choose an extra-long-bed/mattress combo for taller guests. Extra long twins are 80" long, while standard twins are only 75" long. A standard twin can comfortably sleep someone up-to 6' tall. A man above 6' will need an extra long mattress, which can accommodate someone up-to 6'6"tall. I guess it all depends on how often you see yourself hosting very tall people!
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