We offer both maintenance services and detailing services. Both can be used by any customer, with the maintenance services only for vehicles that are in decent shape and obviously maintained.
We learned our lesson that the OP mentioned a long time ago. Customers hear "vacuum" and "wipedown" and expect their leather seats to be deep cleaned, and all the sand and pet hair removed.
So for new customers we thoroughly inspect the vehicle with them, and if needed force them to bump up to our details. If the car is newer and in decent shape we'll just do a maintenance package on them if thats all they want to spend.
Some guys on here mentioned that they do not even offer lower packages, and I understand why. But they've also said that they've lost business over it, and are fine with it. I'm not fine with that though, I want every opportunity. Many people spend a night online looking at websites and services and prices without calling or emailing in for information. If you're shutting them down right away, you're definitely losing money. Having decently cheap prices on basic interior options is good because it'll at least get me a phone call or a walk-in. I can then use my astonishingly good looks and persuasive personality to upsell into a bigger job when needed.
The answer is of course : There is no right way or wrong way, its the way that works better for your demographic and business.
But in either case, if you are not inspecting the vehicle with your customer and allowing them to pick off your menu without your input, you're doing yourself a disservice.
One of the BIGGEST mistakes we do is to NOT LISTEN to your customer. ASK your customer to point out the areas of concern, LISTEN to them intently, THEN offer them a package that suits their needs as they relayed them to you. If the price is too high you can then say "Ok if we don't do THIS.. Your price will be XXX" and you can start stripping out services if needed to fit the budget.