Men are fixers so are often always trying to improve things that we women couldn't care to put the effort into. My husband is one of those business always looking for ways to excel, advance and be better than the best. I think we just kinda found a groove for him offering some suggestions and my politely turning them down lol.
I would just recommend talking about it on a day where everyone is happy, calm and the topic hasn't yet come up. So don't tell him you don't want suggestions for improvement right after he has given a suggestion for improvement! Just casually one day mention that you appreciate all his suggestions and idea and you hope he doesn't mind that you don't attempt them all but that after working 10hr days with the daycare you just can't put anymore time and effort into the daycare once you close for the day. Plant the seed that you aren't ignoring him but you just don't have it in you to do his suggestions.
As much as the daycare is a business it is a very personal one. AND it is a business with limits. If you are at full capacity then hardcore advertising is wasted effort as the payoff is minimal. This is different then most businesses that can expand with demand. Also, the income is capped so all the effort and money and time put in to making the daycare space better and better pays off a bit, but ultimately is extra effort that isn't really needed.
Try comments like "oh neat idea, but with my capped income I'd rather save my time and money to spend with you".