As funny of a suggestion as it sounds, a lot of communities use the rooftop advertising. If you're near a freeway, you'll be on the traffic report in the AM
Here's an idea, and I don't know if it would work, but I think it would definitely get the attention you're looking for...
So no to banners, no to signs, no to balloons, and No on the human directionals holding the sign.
What about getting a group of your resident's kids, or even kids from the local high school/Jr High. Put them all in brightly colored t-shirts (Lime Green, Electric Pink, Happy Banana Yellow, etc.) that invite traffic in (Please use something better than NOW LEASING, but that's the general message idea) and then pay them to stand out on the street with ribbon dancer ribbons, balloons, jump ropes, anything that they could do out there that looks active and fun. The shirts have the message, no signs, and that kind of activity always attracts attention. All you'd have to supply is really the soda and snacks and find a parent to supervise. You could pay the group by donating to it's funding (if it was a local organized youth group of some kind) or by offering the kids a pizza party at the local joint at the end of the day/weekend. A lot of places have a large front entry lawn area, and this is a perfect place to organize your non-sign holding Human Directionals. Also, training them to tell people to have a great day as they depart your property would be a great cherry on the sundae!