Another option to around the room or an island shapes is an L shaped layout against two walls. The two legs can be 12 ft long and each 5 ft or 6 ft wide. An outside loop can have larger that 027 curves.
An average reach from an edge is at least 4 ft, maybe 5 ft if tall. Grabbers can be used to reach farther or one length can be shortened to 11 ft to help access.
My 40 year old layout is near the sizes mentioned above but the layout was on the floor for 30 years and strong enough to walk on. It is full of 027 track with 31 switches where as your talking about a simpler single track plan with bigger diameter curves which will allow access panels to be used to reach along the walls.
The choice is limited track with large curves or sharper curves and more track with multi loops and switching an option. How do want to operate or watch your trains?