B.M.
Why don't you organize a block/neighborhood party? You still have time this summer and you could get some other parents to help so the burden isn't all on you. We did a very simple one where we put out a flyer on everyone's door, got permission from the city to "close" the street and invited everyone to "bring a dish to share and meet the neighbors. This way you could meet the neighbors and your daughter could meet the kids.
Not sure what your neighborhood make-up is, but you can get some simple arts and crafts for the younger kids (we had a bike decorating contest with streamers etc). One of our neighbors had a sound system and did the music. It has since grown into a HUGE annual event. Your fire department will bring a truck for the kids (for free) and they will also open a hydrant. sometimes you can get the dept of sanitation to bring a dumpster for free, so you don't even have a mess to clean up.
My perspective on 2 things in your post:
1. the predator that lives 5 houses down isn't as scary as the one that isn't registered and you don't know where he lives. Or as scary as the one who hasn't been caught yet, but will be registered predator in 5 more years.
2. "some parents on the street that drink" - I'm not sure what you mean. I drink. Most of my friends drink. Some of my friends don't drink, but I don't hold that against them ;-) I'm a really responsible parent, as are my friends who both do and don't drink. At the block parties now there is a margarita machine for the adults and a snow cone machine for the kids. No one gets wasted or drinks irresponsibly - so I'm not sure why that would be a problem. If you exclude you or your daughter being friends with anyone who ever drinks responsibly, you will have a very very very short list of people to be friends with. If they drink to the point of being drunk in front of the kids that is another issue.
Having said that - I live in Chicago, pretty near to downtown. My 9 year old does not go outside without me. Ever. Under any circumstance. At all. Not even to get the mail. And I wouldn't ever be confused with being overprotective. To me that is just good sense.