Royal Oak, MI: 4bed or 3bed, better value for rental?

[Matt Noble]

I am a first time home buyer and just purchased a 4 bed 1 bath bungalow in Royal Oak. I am renovating the property and then going to rent the property out. It currently has 2 bedrooms and 1 bath downstairs and 2 bedrooms upstairs. I would like to add a bathroom upstairs but there is little room to add one unless I build a dormer which is quite an investment I am learning. I could convert the upstairs to a master suite and have that bathroom, or make the large investment of adding the dormer and converting the house to a 4 bed 2 bath. 

(it is on  crawl space so no option to add a bathroom to the basement)

Since I am new to REI, would it be worth it to add the dormer for the extra rent of a 4 bed 2 bath? or should I save the capital and have it be a 3 bed 2 bath with a master suite?

Any advice would be greatly appreciated!

Thanks