The reason that dinosaurs had large, thick tails had a lot to do with bio-mechanics, and the model of a long, thick tail dragging behind the creature was actually rendered obsolete back in during the major re evaluation of the dinosaurs in the 1980's.
Large Sauropod dinosaurs are now thought to have long, fairly stiff tails which act as counterbalances, with the hips acting as both pivot points, and also as analogues to the towers which support cable stayed and suspension bridges. Long ligaments and tendons radiate from the hips to both the spine and the tail, using the mass of the tail to keep the spine aligned. For theropods like T Rex, the tail balanced the massive head and body, which was held in a more horizontal position.
To me, the use of a large tail suggests that the humanoid creatures are descended from a dinosaur like ancestor, and will also have the largely horizontal body posture of their ancestors. Like T Rex, the head will be forward facing and angled so the creature is looking ahead, and not "down"
"Darren Naish has argued that a large-brained, highly intelligent troodontid would retain a more standard theropod body plan, with a horizontal posture and long tail, and would probably manipulate objects with the snout and feet in the manner of a bird, rather than with human-like "hands"
Hypothetical sapient dinosaur
So given the tail reorders the body plan, then furniture like chairs and so on will also need to be different. Rather than sitting down like we would, the creature would perhaps lower the body to rest on a horizontal surface where the weight is taken from the legs, but the hands/manipulating organs are free and the tail points out the back. This would resemble a bench, except the short end would be pointed at the (low) table or work surface and the long end sticking out like the tail of the letter "T"
Bench seat for a tailed being. The trunk can rest on the padded surface so the table or work bench would be on the right as you look at the picture
While not the answer you were expecting, thinking about the evolutionary reasons for body plans can come up with all kinds of unexpected things, which can add interest and a true sense of how alien the setting actually is.