One really I good idea which they'd used at a nursery ds went to in Canada for a while was to have a one-way mirror from the lobby area into the room where the children are. That way you can actually look in and see how they are without them (or the staff for that matter!) knowing you are there. Great for those times when the kids don't want the parent to leave, but the parent wants to know that they really do settle quickly once they've gone.
One of the criteria I used when choosing a nursery for ds was the amount of time he would get to spend outside/how much outdoor space they had. I really believe that lots of outdoor activities are important for little ones - particularly for boys. Our nursery takes them for daily walks as long as it's not absolutely emptying down (a little bit of rain won't actually hurt them) or way below freezing. It sounds crazy but I rejected places which didn't have wellies and waterproofs on the list of things I had to send in for him! Obviously this isn't important to everyone, and not all nurseries will be lucky enough to be in the kind of setting where they can do that without encountering traffic etc.
Our nursery also does a lot at quite an early stage with them about where food comes from, so they keep chickens and the children help to feed/water them, and collect the eggs, and they grow things like pumpkins so they can water them and watch them grow, and do simple cooking - obviously with a lot of help and supervision. I quite like that as it takes the "giving them good food" ethos a bit further and actually gets them to understand food a bit too (ds recently asked the lady running a cheese stall at our local farmers market if she knew that cheese was made from milk, which comes from cows? Or from sheep or goats or buffalos!)
Other than that, agree with the mixed ages of carers as mentioned before, low turnover of staff (although obviously you can't do much about that if you are only just opening), security, etc.
I'd also look at other non-routine actvities - ours has trips out every so often to a zoo or farm for example, or has people come in with a tractor say, or a shire horse and cart, and the bigger ones do a "show" a couple of times a year.
tbh although you'd obviously want them to be following the early years goals, I'm not over bothered by the places which offer things like languages for 2 year olds.
Perhaps illogically I found the neatest, tidiest, smartest decoration, everything brand new and perfectly tidy places a bit too sterile and designed to appeal to the parents rather than the kids. But then as it's the parents who are paying the bills....
Perhaps you need to decide what your target market (in terms of the parents requirements) is? Think about the type of area the nursery is going to be in, and consider what the likely top priorities of the local parents may be (which might not be the same as the average response you get from mumsnet!). I'm sure in some areas organic everything, early language lessons and visiting ballet teachers would be de rigeur, in others nobody would be bothered if you had turkey twizzlers and chips on the menu every day and TV on all the time (and most places of course would be somewhere in between the two)