When I visited there some years ago, @ 15, I think they had a large HO layout of that area and small layouts in most other scales. It was next to the UP tracks and was a good watching place. It is also in a city park and has a large scale ride-on train just outside.
The zoo is also nearby.
Alamagordo is an interesting area and also has a museum with some railroad info.
And of course the White Sands are not far away.