I would vote bookshelf, since in long term rentals, typically, you want the least amount of things you will need to fix, as possible.If short term rental, than Murphey bed would be my vote, typically.

Two are 3 bed 2 bath, and one is 4 bed 2.5 bath.

Each unit is 2 bed 1.5 bath.

Builders do this a lot to add extra potential sleeping area without having more bedrooms than septic is rated for.I have seen people put beds in the loft after closing or even close in this area to make an unofficial bedroom.Just be clear in your pictures and description and you should be fine either way.

Home was nice 4 Bed 3Bth under $550K with a decent size lot/yard and it only required 5% down as a New primary.Now I am not sure how big of a home you need but as you can see $100K covers much more in a scenario like that one above. 

I just purchased a SFR 3 bed-1 bath and I would love to talk to you about it.

Quote from @Jason Seay: 3 bed 2 bath house. 

Out of bed before 5 am - (I had a separate habitat for starting the day right but then slowly started pushing my time of getting up back2. 

A nice 3 bed 1 bath around 1200 sq ft is easy to buy, cost very little to maintain, rents easy, and is easy to sell to another investor or a homeowner.

We've pre-leased ~225 beds out ~240 already for next year and 90% of our leads come from that.