This is a very broad answer; it depends.

Got anything that might include any details?

I wanted it to be broad. The room is not treated at all the size of a bedroom... Has parallel walls with a drum set.

If the room sounds bad or indifferent then close mic the guitar. Get the snare and cymbals out of the room while you record the guitar. As to mic positioning, that is completely dependent on the guitar, mic's available, and sound goal.

To go even further than John, get the drum set out of ANY area you are recording acoustic instruments with sensitive mics. Its really quite amazing how much ambient sound is generated through sympathetic vibrations to various items in a room. A drum kit is even more sympathetic than the usual, bookcase/furniture/crying baby/glass collection/pink elephant/etc

Your question is way too vague and involves a complete explanation of acoustics vs. recording techniques in a space. Be specific.

My point prezackly DD...

What kind of music, emotion, guitar, strings, voice, room size, shape, furnishings, and available positioning all make a huge difference in certain circumstances.

I generally don't make blind choices... I try to at least have a bit more of a grasp on reality when I walk into a session than making any assumptions. e.g. I'll approach an untreated living room with vaulted ceilings and hardwood floors much different than I would a bedroom with heavy drapes, carpet, lots of furniture and dirty clothes all over the floor. And even the fact the OP is talking about a bedroom with a drum kit isn't really all that specific enough for me to make some type of educated guess as to what I would do.

Sure, it gets me down to a narrower selection of mic's and pre's, but positioning and the final selection are dictated by more than some kind of wrote methodology... this actually takes a bit of thinking through the problems you experience when you're dialing in on the sound you want.

I wouldn't necessarily approach an aggressive spirited rock ballad demo, sung by a 30 year old male who can work a mic, the same as I would approach a teenage girls singing a love ballad about her life to that point. They're just completely different in more than just the music and emotion... as you now have to account for the environment, and how much of that environment to include or exclude.