Well, eating only healthy snacks and drinking only water and milk was a turn off to many kids so I began buying some of the sunships, capri suns, and such. One announced "I will be bringing my own snacks from now on since you people NEVER have ANYTHING to eat." I also found out that some kids do not eat kid portions after they complained about starving and kept asking for more.
I found they LOVE hot snacks after school as most don't fix them(mini pizzas, chicken nuggets, brownies. I sometimes let them help which they love.
Having a trampoline is a big pull and it gets used more than a playground with an elevated fort. Also, we have razor scooters, a plasma car, bikes, skates, and tons of balls for outside. We learned to keep the ones they outgrow so we can all have something to do at the same time.
We do crafts that I demonstate and help with occasionally and that includes gifts for parents(valentines, christmas ornaments). That is always a hit no matter how it turns out. If you have carpet, I would put out a big, flat piece of cardboard for the crafts outside. Some kids have not worked with paints and glue very much. I would not allow moon sand, moon dough, or sand.
Even with 8 year olds and a tile floor, it gets everywhere. I hate it.
I would say NO to Wii, gameboy, DSi, and computer. These just breed arguements and frankly kids sit on their bums enough. The commercial with a wii party never has worked out like that for us.
I would try to limit playdates to 2 hours so everyone has fun. Between 2 and 2 and a half hours, at least with girls, the conflicts start. Leave them wanting more and encourage parents to come on time. I have babysat a group of kids so parents could go out. These are kids I REALLY know whose parents I know. Sometimes they act like siblings, but it is ok as we are all friends and they know I am not picking on their child or playing favorites. My husband has a 2 hour limit as well.
I am a more the merrier person, but with playdates it is important no child feel excluded. My only likes to play one on one best so that is what we do most. Friends bring all their kids when they come over so it can get to be overwhelming for her after awhile. We also change it up by meeting at a public park where they can skate or ride longer distances and there is no fighting over toys.
When you have kids over, I would not allow neighbor kids to join in. Be polite, but firm. We had a little girl who kept acting ugly and my husband was talking to her. She didn't want to miss out so she said "Look, I don't have to work it out with her because I am just here to play with her toys and the kids she brought home, not her." Of course she has never been back in the two years since.