I would talk to a realtor and make sure it makes sense to remodel before you sell. A buyer might prefer to redo it themselves. A fresh coat of paint is usually a good idea regardless. Do you have photos?

It might help if you put the vanity and shower both on the upper wall. Maybe add 1' to the shower width, and go for a smaller vanity. If you rotate the toilet so it's facing the door, you gain space that might also allow for a deeper shower. I think you could do both of these without moving plumbing.

Can you move the door?

I agree with kmcg. On the upper wall, which is 77" I believe, have a 42" wide shower and a 35" wide vanity. The vanity should only be 18-20" deep. The vanity can abut the shower wall, ideally done in glass. If you have other storage very near the master bath and require little storage actually in the bathroom, I would just have a counter with sink stretching from the shower wall to the opposite wall - this will make the room feel larger and will save you lots of money. But if storage is a premium you will need a vanity with storage for the potential buyers.

The shower depth will be 52", so a 42" x 52" shower (a very good size I think). The 24" shower door or opening will be more or less opposite your window.

Rotate the toilet as kmcg suggests - you will still have 44" for the toilet, lots of room. You could have some storage in a cabinet or shelves above the toilet. towels under the window.

Keep the door where it is, very minor plumbing changes. Keep the same toilet and faucet/sink if they are decent, you should be able to keep the costs in check.

Shellking's suggestion to speak to a realtor is a good one, but that tiny shower is a real issue I think, especially if the rest of the house is lovely and recently renovated. Buyers will expect the same level of attention in the master bath I think.