@Nyomie, I agree that space around the bed is important. To start with, we had just enough space on one side of a queen-sized bed for a small adult to squeeze through. Two or three guests complained about that (just to us, thankfully, and not in the review). We reconfigured our rooms to have enough space on both sides of the bed for adults to maneuver.
As to beds, I think the two singles that can form a king is ideal in one room, especially if the singles can they be secured together so they use king bedding and seem like an actual king. Having a king is a real advantage. But having the two singles could be advantageous for your market, too.
For the other, a double sounds better, as a queen is too tight.
We have a queen in one room and a double in the other. Both of our rooms get rented, and lots of couples have used the double. I wish we had the option of a king, but our rooms aren’t big enough.