Raised petals can reduce the area available for a cat to stretch, although their effect depends on the flower's shape and construction. Some form a soft edge around a broad centre; others occupy a substantial part of the quoted diameter.
Consider both the horizontal resting area and the space at body height. A petal that curves inward may feel more restrictive than a low outward-facing border. Check whether the cat can enter easily, turn around and rest without being pressed against the support. Decorative softness should not be mistaken for structural support: do not assume a petal is designed to carry the same load as the centre. Ask how the manufacturer defines the bed dimensions and use that information to compare models. A larger outer flower is not automatically a roomier sleeping place.
Compare a top view with a side view. The top view reveals the centre's outline; the side view reveals whether the border leans over that centre. Together they distinguish a broad open bed from a narrower, bowl-shaped space.
For product comparisons alongside this advice, see Floral Canopy and Arbor Retreat. The details below explain their sizes and uses.
Further reading: cats.org.uk; cats.org.uk.
Floral Canopy
Arbor Retreat
Linden wooden cat tower