Need some printing advice

[swatcop169]

I have a lady that wants to purchase three of my prints.
The sizes on the prints are:

1. 5100 x 2755
2. 5065 x 1718
3. 5105 x 2542

Whats the best print size for these photo's? I belive I can have up to 30" 40" printed. But I want the best size for these.

[swatcop169]

Here's the information that was given to me.

"Well, the Panoramic shots need to be able to fit underneath a mat inside a frame, with the open area inside the mat measuring 22x9, give or take a few inches. Would that be a medium? Large?"

If this helps any.