It's difficult to answer, since you have provided no clues about your planting zone, soil, or sunlight conditions. Wisteria, climbing roses, jasmine and bougainvillea come to mind. My favorite of the three for a porch is wisteria, but depending on your growing conditions, that may be more than your porch can handle.

Huh? WHAT neighbors? lol
How about honeysuckle?

Hi. I'm sorry. I believe I am in zone 5..(NE Ohio)

The neighbors are the ones that you can see the basketball hoop and driveway, but not thei house in that picture. They have three small children under the age of 5 and if the Mother sees us sitting there she has a tendancy to leave them outside for us to watch. Nice eh? So I have avoided sitting on my front porch for the last two years, or I run inside when I see their car pulling up that driveway and the children see us sitting out. I do not mind them sometimes, but sometimes you just want to sit and have a glass of wine and be ALONE. Know what I mean? Anyhow I am researching the sugestions above. Please keep them coming. :)

Oh and we have some weird spil here. Kind of clayish and I get full morning sun on the front porch.

With a wisteria, what type of trellis or arbor would I need to provide? My Mother has one that basically consumed a kissing bench, but she does not prue ever I think. Her back yard looks like it could use a good chain saw. (Sorry Mom)

Sweet peas? You can grow different varieties that bloom in the cool of spring/early summer as well as ones that can better handle the heat of summer. But they're annuals. So are black-eyed susan vines and hyacinth beans.

Maybe you could put in border along the property line of stinging nettle and thorny stuff (roses, barberry, etc)??? Brings new meaning to biological weapons!!!

thorny stuff...that sounds good. LOL.

Maybe we should just plant a FENCE!!!!

How about Actinidia kolomitka? Check it out on the link below. Also, do a search for other photos of the foliage, this link's photo doesn't do it justice.

Here is a link that might be useful: Kiwi Vine

Suggest you stay away from Kiwi and Wisteria. Both are very heavy vines which can 'eat' the house. About 40 years I was faced with a similar situation. We constructed a normal full trellis that stretched from post to post painted the house color. It was attached in such a manner that we could lay it back for house painting when necessary. Then I planted two white seedless grape vines at the base. Grapes should be cut back in early spring and quickly regrow. Easy to secure and train on a trellis. And, you have a food crop. Last year I was back in that town and stopped at the old homestead. Introduced myself. Their first question was, "Did you plant the grapes? We love them!" It was fun to revisit all my original plantings which had been well cared for by various owners. Very few changes in the original plan had been made over the years.

I know this is probably too late, but I saw the best idea at a house with a porch just like yours. They hung a frame latice with two chins from the ceiling of the porch over the railing that filled in the space then they grew sweet autum clematis from the ground up.

Why not hang a couple hanging baskets down from the ceiling. Fern or fuschia or torenia or angelonia.

I'd suggest multiple layers for privacy. You definitely have room for an evergreen, perhaps a specimen conifer, between the street and your house and even a mixed hedge along the property line. Personally, the view across the street like that at another house would drive me crazy. I would feel like I was on display.

For the porch, I'd choose a vine that will not tear your house down in 10 years (forget about Wisteria). Something like a climbing rose although be careful to plant outside the porch eave so that the plant can receive sufficient water. I have a similar porch and have a pink Mandevilla vine planted in a container on the porch. It climbs up the railing and post during the summer. I cut it back before the first frost and bring it inside to overwinter.