Right so first thing you need to do is check your meal plan vouchers.( I can't remember if Cheyenne is standard or plus). You will have breakfast and one other meal covered for every night of your stay. If standard that will be up the buffet standard (But not not all buffets), plus Will be all buffets, some sit downs and certain sittings of buffello Bills wild west show.
Next decide if you want to character dining. You will need to top up your meal vouchers for this. Character dining is a spectacular way to meet characters.
Fast food in the park ranges between 11€ and €15 per a person. Some meals are shareable if you make the most of breakfast and know you have a big dinner: ive done this with loaded fries at fuenta del oro and heard it done with fish and chips at Toad Hall and pizza. If you are happy to do the 5 min wander into the village there is real of sandwich at about €7-8 and McDonald's.
You need to book buffets and sit down. Depending on the time if year, Where you what to eat and whether you prioritise keeping costs down over location varies where your best eating. For example it might be worth checking out the price to upgrade to full board at standard or plus level. The value for money this offers is phenomenal. When we used to do full board plus we didn't eat or drink anything else anywhen else in the day and ate at some spectacular restaurants. We refilled kids cups at drinks fountain (take mini squash) and I took a flask of coffee.
We give everyone (adults and children) fixed spending money for time there and they choose how and when they spend it. Lot out for anything that has a sale sticker on (the sale prices are good). Toys are about the same price as here. Clothes are expensive but fantastic Quality (for a hoody €40-60 tshirt €20-30, these both come down significantly in a sale). Direct the kids towards the pins in you are looking for a cheap (start at€7) souvenir. If you are keeping costs down pick up a (disney) lanyard from ebay prior to going. If they get into it, they'll be looking for pins everywhere they sometimes have unique ones in some shops. Mugs and bowls are also reasonable value for money (about €10-€12). I have a fair stash of blankets (some from 10 years+ ago) and the foldable bags (That are fantastically usefully) that are till bargains. If you are going October-about March, I take one of these folding bags so when we go into a restaurant or auditorium everyone can shove in hat's gloves and scarfs so they dont get lost.
I've done it where we've had a full board meal plan and the only additional spending was €50-€100 per a head souvenirs. I've also done it fair fair more extravagantly
The facebook group "Disneyland Paris for Brits" has some awesome document in the files section, including a meal plan top up costs (e.g. standard voucher to character dining) document. It's also worth watching a couple of you tube videos to get a better overview "see you main street" are the best. they do videos on all the major hotels, the meal plans, the restaurants etc.