Its impossible to give you a floor plan without proper room measurements, a proper location of a window, entry door, and existing closet. If you're looking for a proper answer, draw out the room on graph paper and attach it. Your measurements don't have to be 100% perfect in this case. Just try to get it to within an inch on each wall. Window height is also important, as maybe there can be usable space below. Also measure up to the trim, not the door or window opening.

In addition to the room measurements. I have a bunch of other questions some are below:
1.I want to know what they're storing in their closet ( i.e. shoes, dresses, pants, etc)
2. Who is planning on using the closet ( him, her, both, kids, handicap accessable)
3. Heights of the people.
4.if you're converting a guest room, are you thinking of an island ( what about budget)

There are a bunch more, but those are the basics.

As I said though, without accurate measurements, its impossible to help.