This is gonna sound dumb...but car washes. That's right, I said car washes. FUCKING GOLDMINE's. I've got a buddy who owns 3 of them and they are cash cow's. You're biggest problem is the EPA and all of the clean water filtration you have to install when building, that and keeping the cashiers from stealing, since it's almost all cash. You can own the land or lease it. Depending on location, owning it is probably a better way to go.
I had 3 partners going in on a new car wash build a couple of years ago, but one of the investors was going through a divorce and things got all fouled up. Probably good it didn't go through since the economy tanked right after. This was a fully automated wash with the tunnel. However, even the do-it-yourself car washes are big money makers.
So if I was going to try and become a millionare with a brick & mortar type business, a chain of car washes would be it. Or laundromats...another cash maker.
Car washes are certainly a gold mine - I also know a millionaire from Car Wash revenues. He owns several of the Wash/Detail centers that upsell you when you drive in - unbelievable how much he made. He even had a little cofee shop inside to feed you while you waited..... but what you are talking about is a lot of work - marketing and otherwise. I mean, a lot of cash up front, management, branding, marketing, EPA (as you stated), what you are talking about is a big league major endeavor. Though the self serve ones would be much cheaper - just find the Real Estate - of course if we are talking about cash cows..... Mini Storage!