Agree with most of what the guys say. Hesitate to disagree with Chugman, who is, of course, THE Man:
1.) You gotta have a bar.
2.) Since you have a bar, you're gonna need a bathroom.
3.) Don't like carpet on the floor with the poker guys drinking, playing cards, watching the ballgame, and watching the trains-often simultaneously. Tile is the way to go, IMO. Its a lot easier to clean when they spill, and you won't have to replace it every few years. A living room area, with carpet and couches, big screen TV, is the ideal. If you have the space, it's a lot more comfortable to watch all those ballgames.
4.) Don't like florescent. (Sorry, Chugman) Potentially noisy, and too harsh. With the advent of LED light bulbs, put in regular ceiling fixtures, utilizing warmer, energy saving LED bulbs.
5.) The more 110 power boxes you have, the more flexibility you have.
6.) Pool table is a great option if you have the space. Games too. On the left is an original sit down table Pac-Man machine. Guys like it, wives adore the thing....
7.) The more you can fit, the more you should. The bowling machine is 50+ years old. The Slugfest baseball game is great, not sure how old. Both run like champs. Great stuff for New Years parties. BTW, you gotta have a guy near you, so he can come to the house in case you need service. Rarely, but every 10 years or so.
8.) Run a dehumidifier, spring, summer, and fall.
9.) Double-track your overhead train. Two trains (I run four) are better than one. Use command control, DCS or Legacy, and run your trains from your bar with the remote.
10.) Light up your bar/trainroom as much as you can. Use as many effects as you can. Install a great sound system. That bar center fabric covers a large speaker, one of 7 around the room. 50 years old and they all sound great.
Hope this gives you some ideas. I'm a retired teacher, hardly wealthy. My father built this entire basement himself. He started with bare concrete. He built the walls, ceiling, floor, bar, electric, speaker system, rooms, etc. All the trains, fixtures, pics, lights, electronic games, are what I added to what was here when we moved in.
All your plans will need to be adjusted as you go. Best money saving tip? Go to Lowes and Home Depot and do it yourself. It may even take a few years, but, that's half the fun.
Your guys will love it.
Best regards,
Jerry