Hi there,
I guess it comes down to how you wish to run your layout. If you plan to have an engine yard mostly for storage and display of your locomotives, and aren't as concerned about the operations of adding a locomotive to a train, then a turntable certainly isn't a neccesity. A couple of yard tracks, an optional engine house or shed, a sanding tower and fueling facilities should do nicely to convey the look.
One alternative to the turntable is a transfer table; its a track on a bridge that moves sideways in a rectangular pit to align with several tracks at the end of the pit. It would still take a bit of space, though not as much as the radiating roundhouse tracks off a turntable.
Another option is the wye, that curved traingle configuration of tracks and turnouts that can be used to turn a loco around but these take up a lot of real estate too.
Do you run steam or diesel locos? There is less need to turn diesels.
Hope this helps!
Ralph
