This question doesn't have an easy answer.
When you do any renovation at all you have to decide why you are doing it. Are you doing it to add value to the home or are you doing it for yourself. What ever you do, you'll want to be sure it's done well and professionally. When you go to resell your home are the majority of buyers going to see the value in your renovation that you do? I live in the Lutherville area and have sold a lot of houses. A lot of buyers in the area are professionals with families who find value in having a master bath, the demand is for 3 and 4 bedroom homes with 2 to 3 bathrooms. The third bathroom doesn't necessarily need to be on the main bedroom level and it can be a half or a 3/4 bath. You may find having a 3rd bathroom on the bedroom level isn't necessarily going to add as much value as it would cost and might not make your house sell any faster.