We have gotten a sketch from every trip we've taken to WDW, so I have some tips on this for anyone who is not familiar with them.
Go to Art of Disney EARLY. Like on your first or 2nd day. Look at all of the "in-stock" pictures because different artists definitely have different styles. (Monica Willis is my absolute favorite because she uses a lot more "force" on her colors so they pop a lot more instead of just light shading with the particular color.) They have a big 3 or 4in binder of ALLLLLLLL of the drawings they can do AND there are special "race weekend" drawings they can do as well (I'll come back and add my Goofy pic that is not in the regular fab-5 section as an example) on a page or 2 toward either the very front or very back of the binder. There are a TON of options for framing. I haven't done the big race-medal thing (yet) but we did get some framed sketches there in the past.
You can buy the in-stock sketches if you like one OR you can get a custom sketch done (you pick out the particular sketch, the colors, if you want it personalized, etc.) Art of Animation resort also usually has some sketches in their shop area since they have an artist working there daily. During MW weekend this year they shipped our drawings to us when they were complete since there is such an enormous demand for them.
Sketches fit into an 11x14 frame when they are on their own.
Customized goofy (race weekend specific sketch and I requested the race weekend title and year)
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As opposed to an in-stock sketch
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