Keep in mind that if they do everything, they will charge you accordingly. I personally don't think it's worth paying mid 4-5 figures for someone to pick out couches, wall art etc. That's a lot of bookings to make that money back before you even start paying down the furniture, let alone the mortgage.
I hired a designer and it costed me around $1000. I had no idea what I was doing and she made some great suggestions and talked me off the cliff from some that would've been awful. Well worth it . . . But spending $5-10K+ would've been excessive and unneeded. She basically gave me some direction and I picked stuff out based on her suggestions. With future properties I will probably pay for an hour of her time to fly some things by her and then take it from there.
Look at what the best performing properties are doing and add your own spin. You will also see some common themes:
-Decor that is appropriate to the theme of the area
-Mix of nice wall hangings and hard objects without being cluttered (again- place appropriate; don't hang an anchor and ship wheel in a mountain cabin)
-Items that provide a "Pop" of color in photos; can be throw pillows, bed skirts, tile backsplash, bar stools, back side of front door etc
-Some coordination of color scheme throughout. The human brain is wired to find and be attracted to patterns
Like I said, a designer can be great but better as a consultant than a full service IMO